diff --git a/lib/oli/authoring/editing/objective_editor.ex b/lib/oli/authoring/editing/objective_editor.ex
index b985241a61f..2e0265d011d 100644
--- a/lib/oli/authoring/editing/objective_editor.ex
+++ b/lib/oli/authoring/editing/objective_editor.ex
@@ -3,10 +3,10 @@ defmodule Oli.Authoring.Editing.ObjectiveEditor do
 
   alias Oli.Repo
   alias Oli.Resources
+  alias Oli.Resources.Revision
   alias Oli.Publishing
   alias Oli.Accounts.Author
   alias Oli.Authoring.Course.Project
-  alias Oli.Repo
   alias Oli.Authoring.Broadcaster
   alias Oli.Authoring.Editing.PageEditor
   alias Oli.Authoring.Editing.ActivityEditor
@@ -14,6 +14,11 @@ defmodule Oli.Authoring.Editing.ObjectiveEditor do
 
   import Oli.Utils
 
+  @doc """
+  Creates a learning objective or sub-objective and optionally associates it with a parent.
+
+  Passing a non-empty `container_slug` associates the new objective with that parent.
+  """
   def add_new(attrs, %Author{} = author, %Project{} = project, container_slug \\ nil) do
     attrs =
       Map.merge(attrs, %{
@@ -62,14 +67,22 @@ defmodule Oli.Authoring.Editing.ObjectiveEditor do
     end
   end
 
+  @doc """
+  Associates an active sub-objective with another objective in the working publication.
+
+  The selected mappings are locked to prevent adding a reference to a child that
+  is being deleted concurrently.
+  """
+  @spec add_new_parent_for_sub_objective(binary(), binary(), binary(), %Author{}) ::
+          {:ok, %Revision{}} | {:error, :not_found | {:not_found}}
   def add_new_parent_for_sub_objective(slug, container_slug, project_slug, author) do
     result =
       Repo.transaction(fn ->
-        with {:ok, resource} <- Resources.get_resource_from_slug(slug) |> trap_nil(),
-             publication <- Publishing.project_working_publication(project_slug),
-             {:ok, revision_to_attach} <-
-               Publishing.get_published_revision(publication.id, resource.id)
-               |> trap_nil(),
+        publication = Publishing.project_working_publication(project_slug)
+        revisions = objective_revisions(publication.id, slugs: [slug, container_slug], lock: true)
+
+        with %{} = revision_to_attach <- Enum.find(revisions, &(&1.slug == slug)),
+             %{} <- Enum.find(revisions, &(&1.slug == container_slug)),
              {:ok, revision} <-
                append_to_container(
                  container_slug,
@@ -80,7 +93,8 @@ defmodule Oli.Authoring.Editing.ObjectiveEditor do
                ) do
           revision
         else
-          error -> Repo.rollback(error)
+          nil -> Repo.rollback(:not_found)
+          {:error, reason} -> Repo.rollback(reason)
         end
       end)
 
@@ -89,8 +103,8 @@ defmodule Oli.Authoring.Editing.ObjectiveEditor do
         Broadcaster.broadcast_revision(revision, project_slug)
         {:ok, revision}
 
-      e ->
-        e
+      error ->
+        error
     end
   end
 
@@ -203,24 +217,178 @@ defmodule Oli.Authoring.Editing.ObjectiveEditor do
     end)
   end
 
+  @doc """
+  Unlinks a shared sub-objective from the selected parent.
+
+  Only the selected parent and child mappings are locked. The transaction checks
+  that another active parent remains, so unlinking cannot create an orphan.
+  """
+  @spec remove_sub_objective_from_parent(
+          binary(),
+          %Author{},
+          %Project{},
+          binary() | %{required(:slug) => binary()}
+        ) ::
+          {:ok, %Revision{}}
+          | {:error,
+             :last_association
+             | :not_associated
+             | :not_found
+             | Ecto.Changeset.t()}
   def remove_sub_objective_from_parent(
         revision_slug,
         %Author{} = author,
         %Project{} = project,
-        parent_objective
+        parent_objective_or_slug
       ) do
-    resource = Resources.get_resource_from_slug(revision_slug)
+    parent_slug = objective_slug(parent_objective_or_slug)
 
-    edit(
-      parent_objective.slug,
-      %{
-        children: Enum.filter(parent_objective.children, fn id -> id != resource.id end)
-      },
-      author,
-      project
-    )
+    result =
+      Repo.transaction(fn ->
+        publication = Publishing.project_working_publication(project.slug)
+
+        revisions =
+          objective_revisions(publication.id, slugs: [revision_slug, parent_slug], lock: true)
+
+        with {:ok, sub_objective, parent} <-
+               associated_revisions(revisions, revision_slug, parent_slug),
+             parent_ids <-
+               Publishing.objective_parent_ids(sub_objective.resource_id, publication.id),
+             true <- Enum.any?(parent_ids, &(&1 != parent.resource_id)),
+             {:ok, updated_parent} <-
+               unlink_from_parent(parent, sub_objective, publication, author) do
+          updated_parent
+        else
+          false -> Repo.rollback(:last_association)
+          {:error, reason} -> Repo.rollback(reason)
+        end
+      end)
+
+    case result do
+      {:ok, parent} ->
+        Broadcaster.broadcast_resource(parent, project.slug)
+        {:ok, parent}
+
+      {:error, reason} ->
+        {:error, reason}
+    end
   end
 
+  @doc """
+  Checks whether removing a sub-objective from the given parent would delete its
+  final association. Tagged sub-objectives cannot be deleted.
+  """
+  @spec sub_objective_delete_eligibility(binary(), %Project{}, binary()) ::
+          {:ok, %Revision{}} | {:error, :associated | :not_associated | :not_found | :tagged}
+  def sub_objective_delete_eligibility(revision_slug, %Project{} = project, parent_slug) do
+    publication = Publishing.project_working_publication(project.slug)
+    revisions = objective_revisions(publication.id, slugs: [revision_slug, parent_slug])
+
+    with {:ok, sub_objective, parent} <-
+           associated_revisions(revisions, revision_slug, parent_slug),
+         :ok <- final_association_eligibility(sub_objective, parent, publication.id) do
+      {:ok, sub_objective}
+    end
+  end
+
+  @doc """
+  Deletes an untagged sub-objective and removes its final parent association.
+
+  Only the selected child and parent mappings are locked, sharing the child lock
+  with association creation so unrelated objective edits are not blocked.
+  Parent associations and course-content references are rechecked within the
+  transaction before deletion. Objective-association writers share the child
+  mapping lock; course-content reference writers do not.
+  """
+  @spec delete_sub_objective(binary(), %Author{}, %Project{}, binary()) ::
+          {:ok, %Revision{}}
+          | {:error,
+             :associated
+             | :not_associated
+             | :not_found
+             | :tagged
+             | Ecto.Changeset.t()}
+  def delete_sub_objective(revision_slug, %Author{} = author, %Project{} = project, parent_slug) do
+    result =
+      Repo.transaction(fn ->
+        publication = Publishing.project_working_publication(project.slug)
+
+        revisions =
+          objective_revisions(publication.id, slugs: [revision_slug, parent_slug], lock: true)
+
+        with {:ok, sub_objective, parent} <-
+               associated_revisions(revisions, revision_slug, parent_slug),
+             :ok <- final_association_eligibility(sub_objective, parent, publication.id),
+             {:ok, deleted_sub_objective} <-
+               Resources.create_revision_from_previous(sub_objective, %{
+                 author_id: author.id,
+                 deleted: true
+               }),
+             {:ok, _mapping} <-
+               Publishing.upsert_published_resource(publication, deleted_sub_objective),
+             {:ok, updated_parent} <-
+               unlink_from_parent(parent, sub_objective, publication, author) do
+          %{sub_objective: deleted_sub_objective, parent: updated_parent}
+        else
+          {:error, reason} -> Repo.rollback(reason)
+        end
+      end)
+
+    case result do
+      {:ok, %{sub_objective: sub_objective, parent: parent}} ->
+        Broadcaster.broadcast_resource(sub_objective, project.slug)
+        Broadcaster.broadcast_resource(parent, project.slug)
+        {:ok, sub_objective}
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
+  defp associated_revisions(revisions, revision_slug, parent_slug) do
+    with %{} = sub_objective <- Enum.find(revisions, &(&1.slug == revision_slug)),
+         %{} = parent <- Enum.find(revisions, &(&1.slug == parent_slug)),
+         true <- sub_objective.resource_id in parent.children do
+      {:ok, sub_objective, parent}
+    else
+      nil -> {:error, :not_found}
+      false -> {:error, :not_associated}
+    end
+  end
+
+  defp final_association_eligibility(sub_objective, parent, publication_id) do
+    case Publishing.objective_parent_ids(sub_objective.resource_id, publication_id) do
+      [parent_id] when parent_id == parent.resource_id ->
+        case Publishing.objective_referenced?(sub_objective.resource_id, publication_id) do
+          true -> {:error, :tagged}
+          false -> :ok
+        end
+
+      _parents ->
+        {:error, :associated}
+    end
+  end
+
+  defp unlink_from_parent(parent, sub_objective, publication, author) do
+    with {:ok, updated_parent} <-
+           Resources.create_revision_from_previous(parent, %{
+             author_id: author.id,
+             children: Enum.reject(parent.children, &(&1 == sub_objective.resource_id))
+           }),
+         {:ok, _mapping} <- Publishing.upsert_published_resource(publication, updated_parent) do
+      {:ok, updated_parent}
+    end
+  end
+
+  defp objective_revisions(publication_id, opts) do
+    publication_id
+    |> Publishing.get_objective_mappings_by_publication(opts)
+    |> Enum.map(& &1.revision)
+  end
+
+  defp objective_slug(%{slug: slug}), do: slug
+  defp objective_slug(slug) when is_binary(slug), do: slug
+
   @doc """
   Detaches an objective from all unlocked pages and activites that currently reference it.
 
diff --git a/lib/oli/publishing.ex b/lib/oli/publishing.ex
index ce0a2d43ea2..717d69c3ada 100644
--- a/lib/oli/publishing.ex
+++ b/lib/oli/publishing.ex
@@ -808,10 +808,19 @@ defmodule Oli.Publishing do
     end)
   end
 
-  def get_objective_mappings_by_publication(publication_id) do
+  @doc """
+  Returns active objective mappings for a publication.
+
+  Pass `lock: true` only inside a transaction to lock the current mapping and
+  revision rows while enforcing a cross-revision invariant. Use `slugs: [...]`
+  to restrict the query to selected objective revisions.
+  """
+  @spec get_objective_mappings_by_publication(integer(), keyword()) ::
+          [%PublishedResource{}]
+  def get_objective_mappings_by_publication(publication_id, opts \\ []) do
     objective = ResourceType.id_for_objective()
 
-    Repo.all(
+    query =
       from mapping in PublishedResource,
         join: rev in Revision,
         on: mapping.revision_id == rev.id,
@@ -820,6 +829,38 @@ defmodule Oli.Publishing do
             mapping.publication_id == ^publication_id,
         select: mapping,
         preload: [:resource, :revision]
+
+    query =
+      case Keyword.fetch(opts, :slugs) do
+        {:ok, slugs} -> from [mapping, rev] in query, where: rev.slug in ^slugs
+        :error -> query
+      end
+
+    query =
+      case Keyword.get(opts, :lock, false) do
+        true -> from mapping in query, order_by: mapping.resource_id, lock: "FOR UPDATE"
+        false -> query
+      end
+
+    Repo.all(query)
+  end
+
+  @doc """
+  Returns resource IDs of active objectives that contain the given child in a publication.
+  """
+  @spec objective_parent_ids(integer(), integer()) :: [integer()]
+  def objective_parent_ids(resource_id, publication_id) do
+    objective = ResourceType.id_for_objective()
+
+    Repo.all(
+      from mapping in PublishedResource,
+        join: rev in Revision,
+        on: mapping.revision_id == rev.id,
+        where:
+          mapping.publication_id == ^publication_id and rev.deleted == false and
+            rev.resource_type_id == ^objective and ^resource_id in rev.children,
+        select: rev.resource_id,
+        distinct: true
     )
   end
 
@@ -1454,6 +1495,60 @@ defmodule Oli.Publishing do
     end)
   end
 
+  @doc """
+  Returns whether an objective is referenced by any active page, activity, or
+  selection in a publication without materializing the matching revisions.
+  """
+  @spec objective_referenced?(integer(), integer()) :: boolean()
+  def objective_referenced?(resource_id, publication_id) do
+    page_id = ResourceType.id_for_page()
+    activity_id = ResourceType.id_for_activity()
+
+    sql = """
+    SELECT
+      EXISTS (
+        SELECT 1
+        FROM published_resources AS mapping
+        JOIN revisions AS rev ON mapping.revision_id = rev.id
+        WHERE mapping.publication_id = $1
+          AND rev.deleted IS FALSE
+          AND (
+            (
+              rev.resource_type_id = $2
+              AND jsonb_path_exists(
+                rev.objectives,
+                '$.*[*] ? (@ == $objective)',
+                jsonb_build_object('objective', $4::bigint)
+              )
+            )
+            OR
+            (
+              rev.resource_type_id = $3
+              AND (
+                rev.objectives->'attached' @> jsonb_build_array($4::bigint)
+                OR jsonb_path_exists(
+                  rev.content,
+                  '$.**.conditions.** ? (@.fact == "objectives").value ? (@ == $objective)',
+                  jsonb_build_object('objective', $4::bigint)
+                )
+              )
+            )
+          )
+        LIMIT 1
+      )
+    """
+
+    %{rows: [[referenced?]]} =
+      Ecto.Adapters.SQL.query!(Repo, sql, [
+        publication_id,
+        activity_id,
+        page_id,
+        resource_id
+      ])
+
+    referenced?
+  end
+
   @doc """
     For a given project's publication id, this function will find all pages and
     activities that have an objective attached to it.
diff --git a/lib/oli/scenarios/directives/objectives_handler.ex b/lib/oli/scenarios/directives/objectives_handler.ex
index 64b1a2e8db6..5996da57b60 100644
--- a/lib/oli/scenarios/directives/objectives_handler.ex
+++ b/lib/oli/scenarios/directives/objectives_handler.ex
@@ -4,6 +4,7 @@ defmodule Oli.Scenarios.Directives.ObjectivesHandler do
   """
 
   alias Oli.Authoring.Editing.ObjectiveEditor
+  alias Oli.Publishing.AuthoringResolver
   alias Oli.Scenarios.DirectiveTypes.{ExecutionState, ObjectivesDirective}
 
   @max_objective_ops 25
@@ -84,14 +85,12 @@ defmodule Oli.Scenarios.Directives.ObjectivesHandler do
     with {:ok, parent} <- get_objective(built_project, parent_title),
          {:ok, child} <- get_objective(built_project, title),
          :ok <- validate_child(parent, child),
-         {:ok, updated_parent} <-
-           ObjectiveEditor.remove_sub_objective_from_parent(
-             child.slug,
-             author,
-             built_project.project,
-             parent
-           ) do
-      {:ok, put_objective(built_project, parent_title, updated_parent)}
+         {:ok, updated_parent, updated_child} <-
+           remove_sub_objective(child, parent, author, built_project.project) do
+      {:ok,
+       built_project
+       |> put_objective(parent_title, updated_parent)
+       |> put_objective(title, updated_child)}
     else
       {:error, reason} ->
         {:error, "Could not remove sub-objective '#{title}': #{inspect(reason)}"}
@@ -103,6 +102,23 @@ defmodule Oli.Scenarios.Directives.ObjectivesHandler do
      "Unsupported objective operation #{inspect(op)}. Expected create, create_sub, or remove_sub"}
   end
 
+  defp remove_sub_objective(child, parent, author, project) do
+    case ObjectiveEditor.remove_sub_objective_from_parent(child.slug, author, project, parent) do
+      {:ok, updated_parent} ->
+        {:ok, updated_parent, child}
+
+      {:error, :last_association} ->
+        with {:ok, deleted_child} <-
+               ObjectiveEditor.delete_sub_objective(child.slug, author, project, parent.slug) do
+          updated_parent = AuthoringResolver.from_resource_id(project.slug, parent.resource_id)
+          {:ok, updated_parent, deleted_child}
+        end
+
+      {:error, reason} ->
+        {:error, reason}
+    end
+  end
+
   defp get_objective(built_project, title) do
     case Map.get(built_project.objectives_by_title || %{}, title) do
       nil -> {:error, "Objective '#{title}' not found"}
diff --git a/lib/oli_web/icons.ex b/lib/oli_web/icons.ex
index f03fd7d7ef7..8a4b2c97e23 100644
--- a/lib/oli_web/icons.ex
+++ b/lib/oli_web/icons.ex
@@ -970,6 +970,36 @@ defmodule OliWeb.Icons do
     """
   end
 
+  attr :class, :string, default: "stroke-black dark:stroke-white"
+  attr :width, :string, default: "24"
+  attr :height, :string, default: "24"
+  attr :stroke_width, :string, default: "2"
+
+  @doc """
+  Renders a decorative unlink icon; the triggering control must provide its accessible name.
+  """
+  def unlink(assigns) do
+    ~H"""
+    <svg
+      width={@width}
+      height={@height}
+      viewBox="0 0 16 16"
+      fill="none"
+      xmlns="http://www.w3.org/2000/svg"
+      class={@class}
+      aria-hidden="true"
+    >
+      <path
+        d="M11.3333 14.6667V13.3333M6 10L10 6M7.33333 4L7.642 3.64267C8.2672 3.01755 9.11513 2.6664 9.99924 2.66646C10.8833 2.66653 11.7312 3.0178 12.3563 3.643C12.9814 4.2682 13.3326 5.11613 13.3325 6.00024C13.3325 6.88434 12.9812 7.73222 12.356 8.35733L12 8.66667M8.66668 12L8.40201 12.356C7.76951 12.9815 6.91587 13.3323 6.02635 13.3323C5.13682 13.3323 4.28318 12.9815 3.65068 12.356C3.33892 12.0477 3.09141 11.6807 2.92249 11.2761C2.75356 10.8715 2.66659 10.4374 2.66659 9.999C2.66659 9.56057 2.75356 9.12649 2.92249 8.7219C3.09141 8.31732 3.33892 7.95027 3.65068 7.642L4.00001 7.33333M13.3333 11.3333H14.6667M1.33333 4.66667H2.66667M4.66667 1.33333V2.66667"
+        stroke="currentColor"
+        stroke-width={@stroke_width}
+        stroke-linecap="round"
+        stroke-linejoin="round"
+      />
+    </svg>
+    """
+  end
+
   attr :class, :string, default: "stroke-black dark:stroke-white"
   attr :width, :string, default: "24"
   attr :height, :string, default: "24"
diff --git a/lib/oli_web/live/workspaces/course_author/objectives/listing.ex b/lib/oli_web/live/workspaces/course_author/objectives/listing.ex
index d2407b21143..feac61d38f2 100644
--- a/lib/oli_web/live/workspaces/course_author/objectives/listing.ex
+++ b/lib/oli_web/live/workspaces/course_author/objectives/listing.ex
@@ -1,8 +1,6 @@
 defmodule OliWeb.Workspaces.CourseAuthor.Objectives.Listing do
   use OliWeb, :html
 
-  import OliWeb.Components.Common
-
   alias OliWeb.Icons
   alias OliWeb.Workspaces.CourseAuthor.Objectives.Actions
 
@@ -10,7 +8,9 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.Listing do
   attr(:revision_history_link, :boolean, required: true)
   attr(:rows, :list, required: true)
   attr(:expanded_slugs, :any, default: MapSet.new())
-  attr(:pending_delete_slugs, :any, default: MapSet.new())
+  attr(:pending_detaches, :any, default: MapSet.new())
+  attr(:pending_deletes, :any, default: MapSet.new())
+  attr(:objective_parents, :map, default: %{})
   attr(:offset, :integer, default: 0)
   attr(:query, :string, default: "")
 
@@ -87,12 +87,14 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.Listing do
               </button>
 
               <button
+                id={"delete-objective-action-#{item.resource_id}"}
                 type="button"
                 class="inline-flex size-9 items-center justify-center rounded p-1 text-Icon-icon-default transition-colors hover:text-Icon-icon-danger active:text-Icon-icon-active focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary"
                 phx-click="display_delete_modal"
                 phx-value-slug={item.slug}
-                aria-label={"Delete #{item.title}"}
-                title={"Delete #{item.title}"}
+                phx-hook="GlobalTooltip"
+                data-tooltip="Delete Learning Objective"
+                aria-label={"Delete Learning Objective: #{item.title}"}
               >
                 <Icons.trash
                   width="14"
@@ -263,11 +265,20 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.Listing do
                       :if={!is_nil(sub_objective)}
                       class={[
                         "group/item flex flex-wrap items-center gap-[10px] rounded-md border bg-Background-bg-secondary p-3",
-                        issue_border_class(sub_objective.any_issue),
-                        MapSet.member?(@pending_delete_slugs, sub_objective.slug) && "opacity-50"
+                        issue_border_class(sub_objective.any_issue)
                       ]}
                     >
                       <% child_expanded? = MapSet.member?(@expanded_slugs, sub_objective.slug) %>
+                      <% detaching? =
+                        MapSet.member?(
+                          @pending_detaches,
+                          {sub_objective.slug, item.slug}
+                        ) %>
+                      <% deleting? = MapSet.member?(@pending_deletes, sub_objective.slug) %>
+                      <% shared? =
+                        length(Map.get(@objective_parents, sub_objective.resource_id, [])) > 1 %>
+                      <% action_label =
+                        if shared?, do: "Detach from learning objective", else: "Delete sub-objective" %>
                       <button
                         type="button"
                         class="flex min-w-0 flex-1 items-center gap-3 rounded-md text-left focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary disabled:cursor-default"
@@ -295,10 +306,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.Listing do
                             ]}
                           />
                         </span>
-                        <span class={[
-                          "min-w-0 flex-1 text-sm font-normal leading-[19.25px] text-Text-text-high",
-                          MapSet.member?(@pending_delete_slugs, sub_objective.slug) && "line-through"
-                        ]}>
+                        <span class="min-w-0 flex-1 text-sm font-normal leading-[19.25px] text-Text-text-high">
                           <.highlighted_title
                             title={sub_objective.title}
                             regex={@highlight_regex}
@@ -306,15 +314,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.Listing do
                           />
                         </span>
                       </button>
-                      <.loader
-                        :if={MapSet.member?(@pending_delete_slugs, sub_objective.slug)}
-                        class="ml-2"
-                        icon_class="text-secondary"
-                      />
-                      <div
-                        :if={!MapSet.member?(@pending_delete_slugs, sub_objective.slug)}
-                        class="flex shrink-0 items-center gap-4"
-                      >
+                      <div class="flex shrink-0 items-center gap-4">
                         <div
                           id={"sub-objective-summary-#{item.slug}-#{sub_objective.resource_id}"}
                           class="flex shrink-0 items-center gap-1"
@@ -384,21 +384,46 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.Listing do
                           </button>
                           <button
                             type="button"
-                            class="inline-flex size-9 items-center justify-center rounded p-1 text-Icon-icon-default transition-colors hover:text-Icon-icon-danger active:text-Icon-icon-active focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary"
-                            phx-click="display_sub_objective_delete_modal"
+                            class={[
+                              "inline-flex size-9 items-center justify-center rounded p-1 text-Icon-icon-default transition-colors focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary",
+                              !detaching? &&
+                                "hover:bg-Fill-Buttons-fill-primary hover:text-white active:text-Icon-icon-active",
+                              detaching? && "cursor-wait opacity-70"
+                            ]}
+                            id={"sub-objective-action-#{item.resource_id}-#{sub_objective.resource_id}"}
+                            phx-click={
+                              if shared?,
+                                do: "detach_sub_objective",
+                                else: "display_sub_objective_delete_modal"
+                            }
                             phx-value-slug={sub_objective.slug}
                             phx-value-parent_slug={item.slug}
-                            phx-value-title={sub_objective.title}
-                            aria-label={"Delete #{sub_objective.title}"}
-                            title={"Delete #{sub_objective.title}"}
+                            phx-hook="GlobalTooltip"
+                            data-tooltip={if detaching?, do: "Detaching…", else: action_label}
+                            disabled={detaching? or deleting?}
+                            aria-busy={to_string(detaching? or deleting?)}
+                            aria-label={"#{action_label}: #{sub_objective.title}"}
                           >
+                            <Icons.unlink
+                              :if={shared? and !detaching?}
+                              width="16"
+                              height="16"
+                              stroke_width="1.5"
+                              class="shrink-0 text-current"
+                            />
                             <Icons.trash
+                              :if={!shared? and !deleting?}
                               width="14"
                               height="15"
                               stroke_width="1.23853"
                               variant="objective"
                               class="shrink-0 text-current"
                             />
+                            <.loader
+                              :if={detaching? or deleting?}
+                              class="flex items-center justify-center"
+                              icon_class="text-Icon-icon-default"
+                            />
                           </button>
                         </div>
                       </div>
diff --git a/lib/oli_web/live/workspaces/course_author/objectives/select_existing_sub_modal.ex b/lib/oli_web/live/workspaces/course_author/objectives/select_existing_sub_modal.ex
index c9ff5e7c022..8d81b3a50cb 100644
--- a/lib/oli_web/live/workspaces/course_author/objectives/select_existing_sub_modal.ex
+++ b/lib/oli_web/live/workspaces/course_author/objectives/select_existing_sub_modal.ex
@@ -1,17 +1,21 @@
 defmodule OliWeb.Workspaces.CourseAuthor.Objectives.SelectExistingSubModal do
   use OliWeb, :live_component
 
-  alias OliWeb.Common.TextSearch
+  alias OliWeb.Components.DesignTokens.Primitives.Button
 
   def update(assigns, socket) do
+    query = Map.get(socket.assigns, :query, "")
+
     {:ok,
-     assign(socket,
+     socket
+     |> assign(
        add: assigns.add,
-       filtered_sub_objectives: assigns.sub_objectives,
        id: assigns.id,
        parent_slug: assigns.parent_slug,
+       query: query,
        sub_objectives: assigns.sub_objectives
-     )}
+     )
+     |> assign_filtered_sub_objectives()}
   end
 
   attr(:add, :string, required: true)
@@ -29,43 +33,95 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.SelectExistingSubModal do
       style="display: block"
       tabindex="-1"
       role="dialog"
-      aria-labelledby="show-existing-sub-modal"
-      aria-hidden="true"
+      aria-modal="true"
+      aria-labelledby={"#{@id}-title"}
       phx-hook="ModalLaunch"
     >
-      <div class="modal-dialog" role="document">
-        <div class="modal-content">
-          <div class="modal-header">
-            <h5 class="modal-title">Select existing Sub-Objective</h5>
-            <button type="button" class="btn-close" data-bs-dismiss="modal" aria-label="Close">
-            </button>
+      <div class="modal-dialog modal-dialog-centered !max-w-[860px]" role="document">
+        <div class="modal-content !rounded-2xl !border !border-solid !border-Border-border-default bg-Surface-surface-background shadow-[0px_2px_10px_0px_rgba(0,50,99,0.10)]">
+          <div class="flex items-center pb-6 pl-8 pr-16 pt-8 sm:px-16 sm:pt-16">
+            <h2
+              id={"#{@id}-title"}
+              class="m-0 text-2xl font-bold leading-8 text-Text-text-high"
+            >
+              Select Existing Sub-Objective
+            </h2>
+            <Button.button
+              variant={:close}
+              class="absolute right-3 top-3 inline-flex !h-11 !w-11 items-center justify-center !opacity-100 text-Icon-icon-default focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary"
+              data-bs-dismiss="modal"
+              aria-label="Close Select Existing Sub-Objective dialog"
+            />
           </div>
-          <div class="modal-body">
-            <div class="container form-container">
-              <TextSearch.render
-                id="text-search"
-                text={@query}
-                event_target={@myself}
-                reset="text_search_reset"
-              />
-              <div class="d-flex flex-column mt-3">
-                <%= for sub_objective <- @filtered_sub_objectives do %>
-                  <div class="my-2 d-flex">
-                    <div class="p-1 mr-3 flex-grow-1 overflow-auto text-truncate">
-                      {sub_objective.title}
-                    </div>
-                    <button
-                      class="btn btn-outline-primary py-1"
-                      phx-value-slug={sub_objective.slug}
-                      phx-value-parent_slug={@parent_slug}
-                      phx-click={@add}
-                    >
-                      Add
-                    </button>
-                  </div>
-                <% end %>
-              </div>
-            </div>
+
+          <div class="px-8 pb-10 sm:pb-16 sm:pl-16 sm:pr-9">
+            <form
+              id={"#{@id}-filters"}
+              class="mb-2.5 flex flex-col gap-3 sm:flex-row sm:gap-6"
+              phx-change="filters_changed"
+              phx-submit="filters_changed"
+              phx-target={@myself}
+            >
+              <label class="relative min-w-0 sm:w-56 sm:flex-none" for={"#{@id}-search"}>
+                <span class="sr-only">Search sub-objectives</span>
+                <i
+                  class="fa-solid fa-magnifying-glass pointer-events-none absolute left-3 top-1/2 -translate-y-1/2 text-Icon-icon-default"
+                  aria-hidden="true"
+                >
+                </i>
+                <input
+                  id={"#{@id}-search"}
+                  name="query"
+                  type="search"
+                  value={@query}
+                  placeholder="Search..."
+                  phx-debounce="250"
+                  class="h-9 w-full rounded-md border border-Border-border-default bg-Background-bg-secondary pl-10 pr-3 text-sm text-Text-text-high placeholder:text-Text-text-low-alpha focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary"
+                />
+              </label>
+            </form>
+
+            <p
+              id={"#{@id}-results-status"}
+              role="status"
+              aria-live="polite"
+              aria-atomic="true"
+              class="sr-only"
+            >
+              {results_status(@filtered_sub_objectives)}
+            </p>
+
+            <p
+              :if={@filtered_sub_objectives == []}
+              id={"#{@id}-empty"}
+              class="m-0 rounded-md border border-Border-border-default px-4 py-6 text-center text-sm text-Text-text-low-alpha"
+            >
+              No sub-objectives match these filters.
+            </p>
+
+            <ul class="m-0 flex list-none flex-col gap-2.5 p-0">
+              <li
+                :for={sub_objective <- @filtered_sub_objectives}
+                id={"existing-sub-objective-#{sub_objective.resource_id}"}
+                class="flex flex-col gap-1 rounded-md py-2 sm:flex-row sm:items-start"
+              >
+                <span class="min-w-0 flex-1 text-base leading-6 text-Text-text-high">
+                  {sub_objective.title}
+                </span>
+                <div class="flex shrink-0 gap-2">
+                  <Button.button
+                    variant={:secondary}
+                    size={:sm}
+                    phx-value-slug={sub_objective.slug}
+                    phx-value-parent_slug={@parent_slug}
+                    phx-click={@add}
+                    aria-label={"Add #{sub_objective.title} to this learning objective"}
+                  >
+                    Add
+                  </Button.button>
+                </div>
+              </li>
+            </ul>
           </div>
         </div>
       </div>
@@ -73,26 +129,26 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.SelectExistingSubModal do
     """
   end
 
-  def handle_event("text_search_change", %{"value" => query}, socket) do
-    query_str = String.downcase(query)
+  def handle_event("filters_changed", params, socket) do
+    {:noreply,
+     socket
+     |> assign(query: Map.get(params, "query", socket.assigns.query))
+     |> assign_filtered_sub_objectives()}
+  end
+
+  defp assign_filtered_sub_objectives(socket) do
+    query = String.downcase(String.trim(socket.assigns.query))
 
     filtered_sub_objectives =
-      Enum.filter(socket.assigns.sub_objectives, fn sub ->
-        String.contains?(String.downcase(sub.title), query_str)
+      socket.assigns.sub_objectives
+      |> Enum.filter(fn sub_objective ->
+        query == "" or String.contains?(String.downcase(sub_objective.title), query)
       end)
 
-    {:noreply,
-     assign(socket,
-       filtered_sub_objectives: filtered_sub_objectives,
-       query: query
-     )}
+    assign(socket, filtered_sub_objectives: filtered_sub_objectives)
   end
 
-  def handle_event("text_search_reset", _, socket) do
-    {:noreply,
-     assign(socket,
-       filtered_sub_objectives: socket.assigns.sub_objectives,
-       query: ""
-     )}
-  end
+  defp results_status([]), do: "No sub-objectives match these filters."
+  defp results_status([_]), do: "1 sub-objective available."
+  defp results_status(sub_objectives), do: "#{length(sub_objectives)} sub-objectives available."
 end
diff --git a/lib/oli_web/live/workspaces/course_author/objectives/sub_objective_delete_modal.ex b/lib/oli_web/live/workspaces/course_author/objectives/sub_objective_delete_modal.ex
index 27f03e49828..7b8a57bb4d3 100644
--- a/lib/oli_web/live/workspaces/course_author/objectives/sub_objective_delete_modal.ex
+++ b/lib/oli_web/live/workspaces/course_author/objectives/sub_objective_delete_modal.ex
@@ -1,6 +1,8 @@
 defmodule OliWeb.Workspaces.CourseAuthor.Objectives.SubObjectiveDeleteModal do
   use OliWeb, :html
 
+  alias OliWeb.Components.DesignTokens.Primitives.Button
+
   attr(:id, :string, required: true)
   attr(:parent_slug, :string, required: true)
   attr(:slug, :string, required: true)
@@ -13,30 +15,47 @@ defmodule OliWeb.Workspaces.CourseAuthor.Objectives.SubObjectiveDeleteModal do
       id={@id}
       tabindex="-1"
       role="dialog"
-      aria-hidden="true"
+      aria-modal="true"
+      aria-labelledby={"#{@id}-title"}
+      aria-describedby={"#{@id}-description"}
       phx-hook="ModalLaunch"
     >
-      <div class="modal-dialog" role="document">
-        <div class="modal-content">
-          <div class="modal-header">
-            <h5 class="modal-title">Delete Sub-Objective</h5>
-            <button type="button" class="btn-close" phx-click="hide_modal" aria-label="Close">
+      <div class="modal-dialog modal-dialog-centered" role="document">
+        <div class="modal-content !rounded-xl border-0 bg-Background-bg-secondary shadow-xl">
+          <div class="modal-header border-Border-border-default">
+            <h2 id={"#{@id}-title"} class="modal-title text-xl font-bold text-Text-text-high">
+              Delete sub-objective?
+            </h2>
+            <button
+              type="button"
+              class="btn-close rounded focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary"
+              data-bs-dismiss="modal"
+              aria-label="Close delete sub-objective dialog"
+            >
             </button>
           </div>
-          <div class="modal-body">
-            Are you sure you want to delete <strong>{@title}</strong>?
+          <div id={"#{@id}-description"} class="modal-body text-Text-text-high">
+            <strong>“{@title}”</strong> is associated only with this learning objective. Removing
+            its final association will permanently delete it from this course. This action cannot be undone.
           </div>
-          <div class="modal-footer">
-            <button type="button" class="btn btn-link" phx-click="hide_modal">Cancel</button>
+          <div class="modal-footer border-Border-border-default">
             <button
+              type="button"
+              id="cancel-sub-objective-delete"
+              autofocus
+              class="rounded-md px-4 py-2 font-semibold text-Text-text-button focus-visible:outline focus-visible:outline-2 focus-visible:outline-offset-2 focus-visible:outline-Fill-Buttons-fill-primary"
+              data-bs-dismiss="modal"
+            >
+              Cancel
+            </button>
+            <Button.button
+              variant={:danger}
               phx-click="delete_sub_objective"
               phx-value-slug={@slug}
               phx-value-parent_slug={@parent_slug}
-              phx-key="enter"
-              class="btn btn-danger"
             >
-              Delete
-            </button>
+              Delete sub-objective
+            </Button.button>
           </div>
         </div>
       </div>
diff --git a/lib/oli_web/live/workspaces/course_author/objectives_live.ex b/lib/oli_web/live/workspaces/course_author/objectives_live.ex
index dd198e688ad..2b5d45b93ca 100644
--- a/lib/oli_web/live/workspaces/course_author/objectives_live.ex
+++ b/lib/oli_web/live/workspaces/course_author/objectives_live.ex
@@ -56,7 +56,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
     project = socket.assigns.project
     author = socket.assigns.current_author
 
-    {all_objectives, all_children, objectives, table_model} = build_objectives(project)
+    {all_objectives, objectives, table_model, objective_parents} = build_objectives(project)
 
     socket =
       assign(socket,
@@ -66,7 +66,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
         table_model: table_model,
         total_count: length(objectives),
         all_objectives: all_objectives,
-        all_children: all_children,
+        objective_parents: objective_parents,
         coverage_model: nil,
         coverage_status: :loading,
         coverage_load_ref: make_ref(),
@@ -78,6 +78,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
         course_content_nodes_by_id: %{},
         course_content_root_ids: [],
         course_content_expanded_ids: MapSet.new(),
+        pending_sub_objective_detaches: MapSet.new(),
         pending_sub_objective_delete_slugs: MapSet.new(),
         query: "",
         search_matching_ids: nil,
@@ -404,7 +405,9 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
             }
             rows={@table_model.rows}
             expanded_slugs={@expanded_objective_slugs}
-            pending_delete_slugs={@pending_sub_objective_delete_slugs}
+            pending_detaches={@pending_sub_objective_detaches}
+            objective_parents={@objective_parents}
+            pending_deletes={@pending_sub_objective_delete_slugs}
             project_slug={@project.slug}
             offset={@offset}
             query={@query}
@@ -421,43 +424,34 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
       |> ObjectiveEditor.fetch_objective_mappings()
       |> Enum.map(& &1.revision)
 
-    all_children =
-      all_objectives
-      |> Enum.reduce([], fn rev, acc -> rev.children ++ acc end)
-      |> Enum.uniq()
+    objectives_by_id = Map.new(all_objectives, &{&1.resource_id, &1})
+
+    objective_parents =
+      Enum.reduce(all_objectives, %{}, fn objective, parents ->
+        Enum.reduce(Enum.uniq(objective.children), parents, fn child_id, parents ->
+          Map.update(parents, child_id, [objective.resource_id], &[objective.resource_id | &1])
+        end)
+      end)
 
     objectives =
-      Enum.reduce(all_objectives, [], fn rev, acc ->
-        case Enum.find(all_children, fn child_id -> child_id == rev.resource_id end) do
-          nil ->
-            mapped_children =
-              Enum.map(rev.children, fn resource_id ->
-                case Enum.find(all_objectives, fn rev -> rev.resource_id == resource_id end) do
-                  nil ->
-                    nil
-
-                  child ->
-                    Map.merge(child, base_coverage_fields())
-                end
-              end)
-
-            [
-              rev
-              |> Map.merge(base_coverage_fields())
-              |> Map.merge(%{
-                children: mapped_children,
-                sub_objectives_count: length(mapped_children)
-              })
-            ] ++ acc
-
-          _ ->
-            acc
-        end
+      all_objectives
+      |> Enum.reject(&Map.has_key?(objective_parents, &1.resource_id))
+      |> Enum.map(fn revision ->
+        children =
+          Enum.map(revision.children, fn resource_id ->
+            case Map.get(objectives_by_id, resource_id) do
+              nil -> nil
+              child -> Map.merge(child, base_coverage_fields())
+            end
+          end)
+
+        revision
+        |> Map.merge(base_coverage_fields())
+        |> Map.merge(%{children: children, sub_objectives_count: length(children)})
       end)
 
     {:ok, table_model} = TableModel.new(objectives)
-
-    {all_objectives, all_children, objectives, table_model}
+    {all_objectives, objectives, table_model, objective_parents}
   end
 
   defp base_coverage_fields do
@@ -717,8 +711,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
   end
 
   defp return_updated_data(project, flash_fn, socket) do
-    {all_objectives, all_children, objectives, table_model} =
-      build_objectives(project)
+    {all_objectives, objectives, table_model, objective_parents} = build_objectives(project)
 
     socket = cancel_async(socket, :objective_coverage)
 
@@ -740,7 +733,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
         table_model: table_model,
         total_count: length(objectives),
         all_objectives: all_objectives,
-        all_children: all_children,
+        objective_parents: objective_parents,
         coverage_model: nil,
         coverage_status: :loading,
         coverage_issue_ids: MapSet.new(),
@@ -1042,35 +1035,7 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
   end
 
   def handle_event("display_add_existing_sub_modal", %{"slug" => slug}, socket) do
-    %{project: project, all_children: all_children, all_objectives: all_objectives} =
-      socket.assigns
-
-    %{children: objective_children} = AuthoringResolver.from_revision_slug(project.slug, slug)
-
-    sub_objectives =
-      Enum.map(all_children -- objective_children, fn resource_id ->
-        Enum.find(all_objectives, fn obj -> obj.resource_id == resource_id end)
-      end)
-
-    modal_assigns = %{
-      id: "select_existing_sub_modal",
-      parent_slug: slug,
-      sub_objectives: sub_objectives,
-      add: "add_existing_sub"
-    }
-
-    modal = fn assigns ->
-      ~H"""
-      <.live_component id="select_existing_sub_modal" module={SelectExistingSubModal} {@modal_assigns} />
-      """
-    end
-
-    {:noreply,
-     show_modal(
-       socket,
-       modal,
-       modal_assigns: modal_assigns
-     )}
+    show_add_existing_sub_modal(socket, slug)
   end
 
   def handle_event("display_delete_modal", %{"slug" => slug}, socket) do
@@ -1135,26 +1100,44 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
 
   def handle_event(
         "display_sub_objective_delete_modal",
-        %{"slug" => slug, "parent_slug" => parent_slug} = params,
+        %{"slug" => slug, "parent_slug" => parent_slug},
         socket
       ) do
     socket = clear_flash(socket)
-    title = Map.get(params, "title", "this sub-objective")
 
-    modal_assigns = %{
-      id: "delete_sub_objective_modal",
-      slug: slug,
-      parent_slug: parent_slug,
-      title: title
-    }
+    case ObjectiveEditor.sub_objective_delete_eligibility(
+           slug,
+           socket.assigns.project,
+           parent_slug
+         ) do
+      {:ok, sub_objective} ->
+        modal_assigns = %{
+          id: "delete_sub_objective_modal",
+          slug: slug,
+          parent_slug: parent_slug,
+          title: sub_objective.title
+        }
+
+        modal = fn assigns ->
+          ~H"""
+          <SubObjectiveDeleteModal.render {@modal_assigns} />
+          """
+        end
 
-    modal = fn assigns ->
-      ~H"""
-      <SubObjectiveDeleteModal.render {@modal_assigns} />
-      """
-    end
+        {:noreply, show_modal(socket, modal, modal_assigns: modal_assigns)}
 
-    {:noreply, show_modal(socket, modal, modal_assigns: modal_assigns)}
+      {:error, reason} when reason in [:associated, :tagged] ->
+        flash_fn = sub_objective_delete_flash({:error, reason})
+        {:noreply, flash_fn.(socket)}
+
+      {:error, reason} when reason in [:not_found, :not_associated] ->
+        {:noreply,
+         put_flash(
+           socket,
+           :error,
+           "The sub-objective association changed. Please refresh and try again"
+         )}
+    end
   end
 
   def handle_event("delete", %{"slug" => slug} = params, socket) do
@@ -1169,34 +1152,66 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
   end
 
   def handle_event(
-        "delete_sub_objective",
+        "detach_sub_objective",
         %{"slug" => slug, "parent_slug" => parent_slug},
         socket
       ) do
     socket = clear_flash(socket)
-    %{project: %{slug: project_slug}, author: %{email: author_email}} = socket.assigns
+    %{project: project, author: author} = socket.assigns
+    operation = {slug, parent_slug}
 
-    if MapSet.member?(socket.assigns.pending_sub_objective_delete_slugs, slug) do
-      {:noreply,
-       socket
-       |> hide_modal(modal_assigns: nil)
-       |> put_flash(:error, "That sub-objective is already being deleted")}
-    else
-      socket =
+    case MapSet.member?(socket.assigns.pending_sub_objective_detaches, operation) do
+      true ->
+        {:noreply, put_flash(socket, :error, "That sub-objective is already being detached")}
+
+      false ->
+        socket =
+          socket
+          |> assign(
+            pending_sub_objective_detaches:
+              MapSet.put(socket.assigns.pending_sub_objective_detaches, operation)
+          )
+          |> start_async({:detach_sub_objective, slug, parent_slug}, fn ->
+            ObjectiveEditor.remove_sub_objective_from_parent(
+              slug,
+              author,
+              project,
+              parent_slug
+            )
+          end)
+
+        {:noreply, socket}
+    end
+  end
+
+  def handle_event(
+        "delete_sub_objective",
+        %{"slug" => slug, "parent_slug" => parent_slug},
         socket
-        |> assign(
-          pending_sub_objective_delete_slugs:
-            MapSet.put(socket.assigns.pending_sub_objective_delete_slugs, slug)
-        )
-        |> hide_modal(modal_assigns: nil)
-        |> start_async({:delete_sub_objective, slug}, fn ->
-          project = Course.get_project_by_slug(project_slug)
-          author = Accounts.get_author_by_email(author_email)
+      ) do
+    socket = clear_flash(socket)
+    %{project: project, author: author} = socket.assigns
 
-          delete_objective_result(slug, parent_slug, project, author)
-        end)
+    case MapSet.member?(socket.assigns.pending_sub_objective_delete_slugs, slug) do
+      true ->
+        {:noreply,
+         socket
+         |> hide_modal(modal_assigns: nil)
+         |> put_flash(:error, "That sub-objective is already being deleted")}
+
+      false ->
+        socket =
+          socket
+          |> assign(
+            pending_sub_objective_delete_slugs:
+              MapSet.put(socket.assigns.pending_sub_objective_delete_slugs, slug)
+          )
+          |> hide_modal(modal_assigns: nil)
+          |> start_async({:delete_sub_objective, slug}, fn ->
+            ObjectiveEditor.delete_sub_objective(slug, author, project, parent_slug)
+          end)
 
-      {:noreply, socket}
+        {:noreply, socket}
     end
   end
 
@@ -1226,6 +1241,34 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
     return_updated_data(project, flash_fn, socket)
   end
 
+  defp show_add_existing_sub_modal(socket, slug) do
+    %{project: project, all_objectives: all_objectives, objective_parents: parents} =
+      socket.assigns
+
+    %{children: objective_children} = AuthoringResolver.from_revision_slug(project.slug, slug)
+    objective_child_ids = MapSet.new(objective_children)
+
+    sub_objectives =
+      all_objectives
+      |> Enum.filter(&Map.has_key?(parents, &1.resource_id))
+      |> Enum.reject(&MapSet.member?(objective_child_ids, &1.resource_id))
+
+    modal_assigns = %{
+      id: "select_existing_sub_modal",
+      parent_slug: slug,
+      sub_objectives: sub_objectives,
+      add: "add_existing_sub"
+    }
+
+    modal = fn assigns ->
+      ~H"""
+      <.live_component id="select_existing_sub_modal" module={SelectExistingSubModal} {@modal_assigns} />
+      """
+    end
+
+    {:noreply, show_modal(socket, modal, modal_assigns: modal_assigns)}
+  end
+
   defp delete_objective(slug, parent_slug, project, author) do
     case delete_objective_result(slug, parent_slug, project, author) do
       :ok -> fn socket -> put_flash(socket, :info, "Objective successfully removed") end
@@ -1234,65 +1277,143 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
   end
 
   defp delete_objective_result(slug, parent_slug, project, author) do
-    %{resource_id: resource_id} = AuthoringResolver.from_revision_slug(project.slug, slug)
+    publication_id = Oli.Publishing.get_unpublished_publication_id!(project.id)
 
-    ObjectiveEditor.detach_objective(resource_id, project, author)
+    with "" <- parent_slug,
+         %{resource_id: resource_id, children: []} <-
+           AuthoringResolver.from_revision_slug(project.slug, slug),
+         [] <- Oli.Publishing.objective_parent_ids(resource_id, publication_id) do
+      ObjectiveEditor.detach_objective(resource_id, project, author)
 
-    objectives =
-      project
-      |> ObjectiveEditor.fetch_objective_mappings()
-      |> Enum.map(& &1.revision)
-
-    {parents, parent_to_detach_slug} =
-      Enum.reduce(objectives, {[], ""}, fn objective, {parents, parent_to_detach_slug} ->
-        case Enum.member?(objective.children, resource_id) do
-          false ->
-            {parents, parent_to_detach_slug}
+      case ObjectiveEditor.delete(slug, author, project) do
+        {:ok, _} -> :ok
+        {:error, _error} -> :error
+      end
+    else
+      _ -> :error
+    end
+  end
 
-          true ->
-            if objective.slug == parent_slug,
-              do: {[objective | parents], objective.slug},
-              else: {[objective | parents], parent_to_detach_slug}
-        end
-      end)
+  defp sub_objective_delete_flash({:ok, _revision}),
+    do: fn socket -> put_flash(socket, :info, "Sub-objective deleted") end
 
-    delete_fn =
-      if length(parents) <= 1 do
-        fn ->
-          ObjectiveEditor.delete(
-            slug,
-            author,
-            project,
-            parent_objective(project, parent_to_detach_slug)
-          )
-        end
-      else
-        fn ->
-          case parent_objective(project, parent_to_detach_slug) do
-            nil ->
-              {:error, :not_found}
-
-            parent_objective ->
-              ObjectiveEditor.remove_sub_objective_from_parent(
-                slug,
-                author,
-                project,
-                parent_objective
-              )
-          end
-        end
-      end
+  defp sub_objective_delete_flash({:error, :associated}) do
+    fn socket ->
+      put_flash(
+        socket,
+        :error,
+        "This sub-objective has other learning-objective associations. Refresh and detach it instead."
+      )
+    end
+  end
 
-    case delete_fn.() do
-      {:ok, _} -> :ok
-      {:error, _error} -> :error
+  defp sub_objective_delete_flash({:error, :tagged}) do
+    fn socket ->
+      put_flash(
+        socket,
+        :error,
+        "This sub-objective cannot be deleted because it is tagged to course content"
+      )
     end
   end
 
+  defp sub_objective_delete_flash({:error, :not_associated}),
+    do: fn socket ->
+      put_flash(socket, :error, "The sub-objective association changed. Please try again")
+    end
+
+  defp sub_objective_delete_flash({:error, :not_found}),
+    do: fn socket -> put_flash(socket, :error, "Could not find that sub-objective") end
+
+  defp sub_objective_delete_flash({:error, _reason}),
+    do: fn socket -> put_flash(socket, :error, "Could not delete sub-objective") end
+
   @impl Phoenix.LiveView
   def handle_async(:objective_coverage, {:ok, result}, socket),
     do: apply_coverage_result(result, socket)
 
+  def handle_async(
+        {:detach_sub_objective, slug, parent_slug},
+        {:ok, result},
+        socket
+      ) do
+    operation = {slug, parent_slug}
+
+    case MapSet.member?(socket.assigns.pending_sub_objective_detaches, operation) do
+      true ->
+        socket =
+          assign(
+            socket,
+            pending_sub_objective_detaches:
+              MapSet.delete(socket.assigns.pending_sub_objective_detaches, operation)
+          )
+
+        flash_fn =
+          case result do
+            {:ok, _revision} ->
+              fn socket ->
+                put_flash(socket, :info, "Sub-objective detached from learning objective")
+              end
+
+            {:error, :last_association} ->
+              fn socket ->
+                put_flash(
+                  socket,
+                  :error,
+                  "This is the final association. Refresh and confirm deletion instead."
+                )
+              end
+
+            {:error, _reason} ->
+              fn socket -> put_flash(socket, :error, "Could not detach sub-objective") end
+          end
+
+        return_updated_data(socket.assigns.project, flash_fn, socket)
+
+      false ->
+        {:noreply, socket}
+    end
+  end
+
+  def handle_async({:detach_sub_objective, slug, parent_slug}, {:exit, reason}, socket) do
+    Logger.error("Sub-objective detach failed: #{inspect(reason)}")
+
+    handle_async(
+      {:detach_sub_objective, slug, parent_slug},
+      {:ok, {:error, :task_failed}},
+      socket
+    )
+  end
+
+  def handle_async({:delete_sub_objective, slug}, {:ok, result}, socket) do
+    case MapSet.member?(socket.assigns.pending_sub_objective_delete_slugs, slug) do
+      true ->
+        socket =
+          assign(
+            socket,
+            pending_sub_objective_delete_slugs:
+              MapSet.delete(socket.assigns.pending_sub_objective_delete_slugs, slug)
+          )
+
+        flash_fn = sub_objective_delete_flash(result)
+
+        return_updated_data(socket.assigns.project, flash_fn, socket)
+
+      false ->
+        {:noreply, socket}
+    end
+  end
+
+  def handle_async({:delete_sub_objective, slug}, {:exit, reason}, socket) do
+    Logger.error("Sub-objective deletion failed: #{inspect(reason)}")
+
+    handle_async(
+      {:delete_sub_objective, slug},
+      {:ok, {:error, :task_failed}},
+      socket
+    )
+  end
+
   def handle_async(:objective_coverage, {:exit, {exception, stacktrace}}, socket)
       when is_exception(exception) do
     Logger.error(
@@ -1308,36 +1429,6 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
     apply_coverage_result({:error, :coverage_load_failed}, socket)
   end
 
-  def handle_async({:delete_sub_objective, slug}, result, socket) do
-    if MapSet.member?(socket.assigns.pending_sub_objective_delete_slugs, slug) do
-      flash_type =
-        case result do
-          {:ok, flash_type} ->
-            flash_type
-
-          {:exit, reason} ->
-            Logger.error("Sub-objective deletion failed: #{inspect(reason)}")
-            :error
-        end
-
-      flash_fn =
-        case flash_type do
-          :ok -> fn socket -> put_flash(socket, :info, "Objective successfully removed") end
-          :error -> fn socket -> put_flash(socket, :error, "Could not remove objective") end
-        end
-
-      socket =
-        assign(socket,
-          pending_sub_objective_delete_slugs:
-            MapSet.delete(socket.assigns.pending_sub_objective_delete_slugs, slug)
-        )
-
-      return_updated_data(socket.assigns.project, flash_fn, socket)
-    else
-      {:noreply, socket}
-    end
-  end
-
   # Kept for compatibility with in-flight messages from older LiveView
   # processes during a rolling deployment. New coverage loads use handle_async/3.
   @impl Phoenix.LiveView
@@ -1349,11 +1440,6 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLive do
     end
   end
 
-  defp parent_objective(_project, ""), do: nil
-
-  defp parent_objective(project, slug),
-    do: AuthoringResolver.from_revision_slug(project.slug, slug)
-
   defp apply_coverage_result({:ok, model}, socket) do
     assessment_buckets =
       selected_assessment_buckets(
diff --git a/test/oli/editing/objective_editor_test.exs b/test/oli/editing/objective_editor_test.exs
index ab390bcbaed..d78a6f81d11 100644
--- a/test/oli/editing/objective_editor_test.exs
+++ b/test/oli/editing/objective_editor_test.exs
@@ -400,6 +400,235 @@ defmodule Oli.Authoring.Editing.ObjectiveEditorTest do
       assert length(children) == 0
       refute Enum.member?(children, subobjective12A_resource_id)
       assert Enum.member?(objective2_children, subobjective12A_resource_id)
+
+      updated_sub_objective =
+        AuthoringResolver.from_revision_slug(project.slug, subobjective12A_slug)
+
+      refute updated_sub_objective.deleted
+    end
+
+    test "remove_sub_objective_from_parent/4 rejects a mismatched parent", %{
+      project: project,
+      author: author,
+      map: %{
+        objective1: %{revision: %Revision{slug: objective1_slug}},
+        subobjective3A: %{
+          revision: %Revision{slug: subobjective3A_slug, resource_id: subobjective3A_resource_id}
+        }
+      }
+    } do
+      assert {:error, :not_associated} =
+               ObjectiveEditor.remove_sub_objective_from_parent(
+                 subobjective3A_slug,
+                 author,
+                 project,
+                 objective1_slug
+               )
+
+      unchanged = AuthoringResolver.from_resource_id(project.slug, subobjective3A_resource_id)
+      refute unchanged.deleted
+    end
+
+    test "remove_sub_objective_from_parent/4 rejects a repeated detach", %{
+      project: project,
+      author: author,
+      map: %{
+        objective1: %{revision: %Revision{slug: objective1_slug}},
+        subobjective12A: %{revision: %Revision{slug: subobjective12A_slug}}
+      }
+    } do
+      assert {:ok, _parent} =
+               ObjectiveEditor.remove_sub_objective_from_parent(
+                 subobjective12A_slug,
+                 author,
+                 project,
+                 objective1_slug
+               )
+
+      assert {:error, :not_associated} =
+               ObjectiveEditor.remove_sub_objective_from_parent(
+                 subobjective12A_slug,
+                 author,
+                 project,
+                 objective1_slug
+               )
+    end
+
+    test "unlink rejects the final association without changing either revision", %{
+      project: project,
+      author: author
+    } do
+      {:ok, %{revision: parent}} =
+        ObjectiveEditor.add_new(%{title: "Parent"}, author, project)
+
+      {:ok, %{revision: child}} =
+        ObjectiveEditor.add_new(%{title: "Child"}, author, project, parent.slug)
+
+      assert {:error, :last_association} =
+               ObjectiveEditor.remove_sub_objective_from_parent(
+                 child.slug,
+                 author,
+                 project,
+                 parent.slug
+               )
+
+      assert AuthoringResolver.from_resource_id(project.slug, child.resource_id).id == child.id
+
+      assert child.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               parent.resource_id
+             ).children
+    end
+
+    test "delete_sub_objective/4 removes an untagged final association atomically", %{
+      author: author,
+      project: project
+    } do
+      {:ok, %{revision: parent}} = ObjectiveEditor.add_new(%{title: "Parent"}, author, project)
+
+      {:ok, %{revision: child}} =
+        ObjectiveEditor.add_new(%{title: "Child"}, author, project, parent.slug)
+
+      assert {:ok, _} =
+               ObjectiveEditor.sub_objective_delete_eligibility(child.slug, project, parent.slug)
+
+      handler_id = {__MODULE__, :deletion_locks, make_ref()}
+
+      :ok =
+        :telemetry.attach(
+          handler_id,
+          [:oli, :repo, :query],
+          fn _event, _measurements, metadata, owner ->
+            case self() == owner and String.contains?(metadata.query, "FOR UPDATE") do
+              true -> send(owner, {:deletion_lock_query, metadata.params})
+              false -> :ok
+            end
+          end,
+          self()
+        )
+
+      result =
+        try do
+          ObjectiveEditor.delete_sub_objective(child.slug, author, project, parent.slug)
+        after
+          :telemetry.detach(handler_id)
+        end
+
+      assert {:ok, deleted} = result
+
+      assert_receive {:deletion_lock_query, params}
+      assert [child.slug, parent.slug] in params
+      refute_receive {:deletion_lock_query, _params}
+
+      assert deleted.deleted
+      assert AuthoringResolver.from_resource_id(project.slug, parent.resource_id).children == []
+
+      refute Enum.any?(
+               ObjectiveEditor.fetch_objective_mappings(project),
+               &(&1.resource_id == child.resource_id)
+             )
+
+      assert {:error, :not_found} =
+               ObjectiveEditor.delete_sub_objective(child.slug, author, project, parent.slug)
+
+      assert {:error, :not_found} =
+               ObjectiveEditor.add_new_parent_for_sub_objective(
+                 child.slug,
+                 parent.slug,
+                 project.slug,
+                 author
+               )
+    end
+
+    test "delete_sub_objective/4 rejects shared children", %{
+      author: author,
+      project: project,
+      map: %{
+        objective1: %{revision: parent},
+        subobjective12A: %{revision: child}
+      }
+    } do
+      assert {:error, :associated} =
+               ObjectiveEditor.delete_sub_objective(child.slug, author, project, parent.slug)
+
+      refute AuthoringResolver.from_resource_id(project.slug, child.resource_id).deleted
+
+      assert child.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               parent.resource_id
+             ).children
+    end
+
+    test "delete_sub_objective/4 rejects activity-tagged children and preserves their final association",
+         %{
+           author: author,
+           project: project
+         } do
+      {:ok, %{revision: parent}} = ObjectiveEditor.add_new(%{title: "Parent"}, author, project)
+
+      {:ok, %{revision: child}} =
+        ObjectiveEditor.add_new(%{title: "Child"}, author, project, parent.slug)
+
+      {:ok, {%{resource_id: activity_id}, _}} =
+        ActivityEditor.create(
+          project.slug,
+          "oli_multiple_choice",
+          author,
+          %{"stem" => "one"},
+          [],
+          :banked
+        )
+
+      activity = AuthoringResolver.from_resource_id(project.slug, activity_id)
+
+      assert {:ok, tagged_activity} =
+               ObjectiveEditor.edit(
+                 activity.slug,
+                 %{objectives: %{"part" => [child.resource_id]}},
+                 author,
+                 project
+               )
+
+      assert {:error, :tagged} =
+               ObjectiveEditor.sub_objective_delete_eligibility(child.slug, project, parent.slug)
+
+      assert {:error, :tagged} =
+               ObjectiveEditor.delete_sub_objective(child.slug, author, project, parent.slug)
+
+      refute AuthoringResolver.from_resource_id(project.slug, child.resource_id).deleted
+
+      assert child.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               parent.resource_id
+             ).children
+
+      assert AuthoringResolver.from_resource_id(project.slug, activity_id).objectives ==
+               tagged_activity.objectives
+    end
+
+    test "shared unlink preserves child revision and course tags", %{
+      author: author,
+      project: project,
+      map: %{
+        objective1: %{revision: parent},
+        subobjective12A: %{revision: child}
+      }
+    } do
+      assert {:ok, tagged_child} =
+               ObjectiveEditor.edit(child.slug, %{tags: [1, 2]}, author, project)
+
+      assert {:ok, _} =
+               ObjectiveEditor.remove_sub_objective_from_parent(
+                 tagged_child.slug,
+                 author,
+                 project,
+                 parent.slug
+               )
+
+      assert AuthoringResolver.from_resource_id(project.slug, child.resource_id).id ==
+               tagged_child.id
+
+      assert AuthoringResolver.from_resource_id(project.slug, child.resource_id).tags == [1, 2]
     end
 
     test "detach_objective/3 preserves tags when removing an objective from a banked activity", %{
diff --git a/test/oli/publishing_test.exs b/test/oli/publishing_test.exs
index be17772b888..79c4b778ae2 100644
--- a/test/oli/publishing_test.exs
+++ b/test/oli/publishing_test.exs
@@ -51,6 +51,307 @@ defmodule Oli.PublishingTest do
     revision
   end
 
+  describe "get_objective_mappings_by_publication/2" do
+    setup do
+      %{publication: insert(:publication)}
+    end
+
+    test "returns only active objectives with their associations preloaded", %{
+      publication: publication
+    } do
+      first_resource = insert(:resource)
+      second_resource = insert(:resource)
+      second = insert_published_mapping(publication, %{resource: second_resource})
+      first = insert_published_mapping(publication, %{resource: first_resource})
+      insert_published_mapping(publication, %{deleted: true})
+      insert_published_mapping(publication, %{resource_type_id: ResourceType.id_for_page()})
+      insert_published_mapping(insert(:publication))
+
+      results = Publishing.get_objective_mappings_by_publication(publication.id)
+
+      assert MapSet.new(Enum.map(results, & &1.id)) == MapSet.new([first.id, second.id])
+
+      first_result = Enum.find(results, &(&1.id == first.id))
+      second_result = Enum.find(results, &(&1.id == second.id))
+
+      assert first_result.id == first.id
+      assert second_result.id == second.id
+      assert first_result.resource.id == first_resource.id
+      assert first_result.revision.id == first.revision_id
+      assert second_result.resource.id == second_resource.id
+      assert second_result.revision.id == second.revision_id
+    end
+
+    test "filters by revision slugs without including deleted or foreign-publication objectives",
+         %{
+           publication: publication
+         } do
+      selected = insert_published_mapping(publication)
+      insert_published_mapping(publication)
+      deleted = insert_published_mapping(publication, %{deleted: true})
+      foreign = insert_published_mapping(insert(:publication))
+      slugs = [selected.revision.slug, deleted.revision.slug, foreign.revision.slug]
+
+      assert [%PublishedResource{id: id}] =
+               Publishing.get_objective_mappings_by_publication(publication.id, slugs: slugs)
+
+      assert id == selected.id
+      assert [] == Publishing.get_objective_mappings_by_publication(publication.id, slugs: [])
+
+      assert [] ==
+               Publishing.get_objective_mappings_by_publication(publication.id,
+                 slugs: ["missing_objective"]
+               )
+    end
+
+    test "locks only the selected mappings when requested inside a transaction", %{
+      publication: publication
+    } do
+      first_resource = insert(:resource)
+      second_resource = insert(:resource)
+      second = insert_published_mapping(publication, %{resource: second_resource})
+      first = insert_published_mapping(publication, %{resource: first_resource})
+      insert_published_mapping(publication)
+      handler_id = {__MODULE__, :objective_mapping_locks, make_ref()}
+
+      :ok =
+        :telemetry.attach(
+          handler_id,
+          [:oli, :repo, :query],
+          fn _event, _measurements, metadata, owner ->
+            case self() == owner and String.contains?(metadata.query, "FOR UPDATE") do
+              true -> send(owner, {:objective_mapping_lock, metadata.query, metadata.params})
+              false -> :ok
+            end
+          end,
+          self()
+        )
+
+      result =
+        try do
+          Repo.transaction(fn ->
+            Publishing.get_objective_mappings_by_publication(publication.id,
+              slugs: [second.revision.slug, first.revision.slug],
+              lock: true
+            )
+          end)
+        after
+          :telemetry.detach(handler_id)
+        end
+
+      assert {:ok, [%PublishedResource{id: first_id}, %PublishedResource{id: second_id}]} = result
+      assert first_id == first.id
+      assert second_id == second.id
+      assert_receive {:objective_mapping_lock, query, params}
+      assert query =~ "ORDER BY"
+      assert [second.revision.slug, first.revision.slug] in params
+      refute_receive {:objective_mapping_lock, _, _}
+    end
+  end
+
+  describe "objective_parent_ids/2" do
+    setup do
+      %{publication: insert(:publication), child: insert(:resource)}
+    end
+
+    test "returns each active parent resource ID once", %{publication: publication, child: child} do
+      first = insert_published_mapping(publication, %{children: [child.id, child.id]})
+      second = insert_published_mapping(publication, %{children: [child.id]})
+      insert_published_mapping(publication)
+
+      assert Enum.sort(Publishing.objective_parent_ids(child.id, publication.id)) ==
+               Enum.sort([first.resource_id, second.resource_id])
+    end
+
+    test "ignores deleted parents, non-objectives, and other publications", %{
+      publication: publication,
+      child: child
+    } do
+      insert_published_mapping(publication, %{children: [child.id], deleted: true})
+
+      insert_published_mapping(publication, %{
+        children: [child.id],
+        resource_type_id: ResourceType.id_for_container()
+      })
+
+      insert_published_mapping(insert(:publication), %{children: [child.id]})
+
+      assert Publishing.objective_parent_ids(child.id, publication.id) == []
+      assert Publishing.objective_parent_ids(child.id, insert(:publication).id) == []
+    end
+
+    test "uses the currently mapped parent revision rather than historical children", %{
+      publication: publication,
+      child: child
+    } do
+      parent = insert_published_mapping(publication, %{children: [child.id]})
+      assert Publishing.objective_parent_ids(child.id, publication.id) == [parent.resource_id]
+
+      assert {:ok, revision} =
+               Resources.create_revision_from_previous(parent.revision, %{children: []})
+
+      assert {:ok, _mapping} =
+               Publishing.update_published_resource(parent, %{revision_id: revision.id})
+
+      assert Publishing.objective_parent_ids(child.id, publication.id) == []
+      assert Resources.get_revision!(parent.revision_id).children == [child.id]
+    end
+  end
+
+  describe "objective_referenced?/2" do
+    setup do
+      publication = insert(:publication)
+      objective_id = insert(:resource).id
+
+      references = %{
+        page: %{
+          resource_type_id: ResourceType.id_for_page(),
+          objectives: %{"attached" => [objective_id]}
+        },
+        activity: %{
+          resource_type_id: ResourceType.id_for_activity(),
+          objectives: %{"first_part" => [], "second_part" => [objective_id]}
+        },
+        selection: %{
+          resource_type_id: ResourceType.id_for_page(),
+          content: %{
+            "model" => [
+              %{
+                "type" => "selection",
+                "logic" => %{
+                  "conditions" => %{
+                    "all" => [
+                      %{
+                        "any" => [
+                          %{
+                            "fact" => "objectives",
+                            "operator" => "contains",
+                            "value" => [objective_id]
+                          }
+                        ]
+                      }
+                    ]
+                  }
+                }
+              }
+            ]
+          }
+        }
+      }
+
+      %{publication: publication, objective_id: objective_id, references: references}
+    end
+
+    for source <- [:page, :activity, :selection] do
+      test "detects an objective referenced only by #{source}", %{
+        publication: publication,
+        objective_id: objective_id,
+        references: references
+      } do
+        insert_published_mapping(publication, Map.fetch!(references, unquote(source)))
+
+        assert Publishing.objective_referenced?(objective_id, publication.id)
+        refute Publishing.objective_referenced?(insert(:resource).id, publication.id)
+      end
+
+      test "ignores deleted #{source} references", %{
+        publication: publication,
+        objective_id: objective_id,
+        references: references
+      } do
+        attrs = Map.fetch!(references, unquote(source)) |> Map.put(:deleted, true)
+        insert_published_mapping(publication, attrs)
+
+        refute Publishing.objective_referenced?(objective_id, publication.id)
+      end
+
+      test "does not count #{source} references from another publication", %{
+        publication: publication,
+        objective_id: objective_id,
+        references: references
+      } do
+        other_publication = insert(:publication)
+        insert_published_mapping(other_publication, Map.fetch!(references, unquote(source)))
+
+        refute Publishing.objective_referenced?(objective_id, publication.id)
+        assert Publishing.objective_referenced?(objective_id, other_publication.id)
+      end
+
+      test "ignores #{source} references in superseded revisions", %{
+        publication: publication,
+        objective_id: objective_id,
+        references: references
+      } do
+        mapping = insert_published_mapping(publication, Map.fetch!(references, unquote(source)))
+        assert Publishing.objective_referenced?(objective_id, publication.id)
+
+        assert {:ok, revision} =
+                 Resources.create_revision_from_previous(mapping.revision, %{
+                   objectives: %{},
+                   content: %{"model" => []}
+                 })
+
+        assert {:ok, _mapping} =
+                 Publishing.update_published_resource(mapping, %{revision_id: revision.id})
+
+        refute Publishing.objective_referenced?(objective_id, publication.id)
+      end
+    end
+
+    test "returns false when there are no mapped references", %{
+      publication: publication,
+      objective_id: objective_id
+    } do
+      insert(:revision,
+        resource_type_id: ResourceType.id_for_page(),
+        objectives: %{"attached" => [objective_id]}
+      )
+
+      refute Publishing.objective_referenced?(objective_id, publication.id)
+    end
+
+    test "ignores references on resource types other than pages and activities", %{
+      publication: publication,
+      objective_id: objective_id,
+      references: references
+    } do
+      insert_published_mapping(publication, references.page |> Map.delete(:resource_type_id))
+
+      insert_published_mapping(
+        publication,
+        Map.put(references.selection, :resource_type_id, ResourceType.id_for_container())
+      )
+
+      refute Publishing.objective_referenced?(objective_id, publication.id)
+    end
+
+    test "does not confuse other facts, page objective keys, or string IDs with objective tags",
+         %{
+           publication: publication,
+           objective_id: objective_id
+         } do
+      insert_published_mapping(publication, %{
+        resource_type_id: ResourceType.id_for_page(),
+        objectives: %{"attached" => [Integer.to_string(objective_id)], "other" => [objective_id]},
+        content: %{
+          "model" => [
+            %{
+              "type" => "selection",
+              "logic" => %{"conditions" => %{"fact" => "tags", "value" => [objective_id]}}
+            }
+          ]
+        }
+      })
+
+      insert_published_mapping(publication, %{
+        resource_type_id: ResourceType.id_for_activity(),
+        objectives: %{"part" => [Integer.to_string(objective_id)]}
+      })
+
+      refute Publishing.objective_referenced?(objective_id, publication.id)
+    end
+  end
+
   describe "learning-model parameter publication resolution" do
     setup do
       Oli.Seeder.base_project_with_resource2()
@@ -261,6 +562,8 @@ defmodule Oli.PublishingTest do
       results = Publishing.find_objective_in_selections(one.resource.id, publication.id)
       assert length(results) == 2
       assert Enum.empty?(Publishing.find_objective_in_selections(two.resource.id, publication.id))
+      assert Publishing.objective_referenced?(one.resource.id, publication.id)
+      refute Publishing.objective_referenced?(two.resource.id, publication.id)
 
       assert Enum.at(results, 0).title != Enum.at(results, 1).title
 
@@ -451,6 +754,9 @@ defmodule Oli.PublishingTest do
       {:ok, %{revision: obj2}} = ObjectiveEditor.add_new(%{title: "two"}, author, project)
       {:ok, %{revision: obj3}} = ObjectiveEditor.add_new(%{title: "three"}, author, project)
 
+      {:ok, %{revision: page_only_objective}} =
+        ObjectiveEditor.add_new(%{title: "page only"}, author, project)
+
       PageEditor.acquire_lock(project.slug, revision.slug, author.email)
 
       activity1 =
@@ -486,7 +792,9 @@ defmodule Oli.PublishingTest do
         )
 
       update = %{
-        "objectives" => %{"attached" => [obj1.resource_id]},
+        "objectives" => %{
+          "attached" => [obj1.resource_id, page_only_objective.resource_id]
+        },
         "content" => %{
           "version" => "0.1.0",
           "model" => [
@@ -526,6 +834,14 @@ defmodule Oli.PublishingTest do
       results = Publishing.find_objective_attachments(obj1.resource_id, publication.id)
 
       assert length(results) == 4
+      assert Publishing.objective_referenced?(obj1.resource_id, publication.id)
+      assert Publishing.objective_referenced?(obj3.resource_id, publication.id)
+      assert Publishing.objective_referenced?(page_only_objective.resource_id, publication.id)
+
+      {:ok, %{revision: untagged_objective}} =
+        ObjectiveEditor.add_new(%{title: "untagged"}, author, project)
+
+      refute Publishing.objective_referenced?(untagged_objective.resource_id, publication.id)
 
       # activity 2 should appear twice since it has the objective attached in multiple parts
       assert Enum.filter(results, fn r -> r.resource_id == activity2.resource_id end) |> length ==
@@ -1642,6 +1958,22 @@ defmodule Oli.PublishingTest do
     end
   end
 
+  defp insert_published_mapping(publication, attrs \\ %{}) do
+    revision =
+      attrs
+      |> Map.put_new_lazy(:resource, fn -> insert(:resource) end)
+      |> Map.put_new_lazy(:author, fn -> insert(:author) end)
+      |> Map.put_new(:resource_type_id, ResourceType.id_for_objective())
+      |> then(&insert(:revision, &1))
+
+    insert(:published_resource,
+      publication: publication,
+      resource: revision.resource,
+      revision: revision,
+      author: revision.author
+    )
+  end
+
   defp activity_parameters(part_id, beta_difficulty) do
     %Parameters{
       schema_version: 1,
diff --git a/test/oli_web/live/workspaces/course_author/objectives_live_test.exs b/test/oli_web/live/workspaces/course_author/objectives_live_test.exs
index 420b4286071..fbf458e653b 100644
--- a/test/oli_web/live/workspaces/course_author/objectives_live_test.exs
+++ b/test/oli_web/live/workspaces/course_author/objectives_live_test.exs
@@ -1358,12 +1358,38 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLiveTest do
       )
       |> render_click(%{"slug" => first_obj.slug})
 
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal button[aria-label='Close Select Existing Sub-Objective dialog'][class~='!h-11'][class~='!w-11'] svg"
+             )
+
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal .modal-content[class~='!border'][class~='!border-Border-border-default']"
+             )
+
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal-title[class~='leading-8']"
+             )
+
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal-filters[class~='mb-2.5']"
+             )
+
       refute has_element?(
                view,
                "button[phx-click='add_existing_sub'][phx-value-slug=#{sub_obj_a.slug}]",
                "Add"
              )
 
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal-results-status[role='status'][aria-live='polite'][aria-atomic='true']",
+               "2 sub-objectives available."
+             )
+
       assert has_element?(
                view,
                "button[phx-click='add_existing_sub'][phx-value-slug=#{sub_obj_b.slug}]",
@@ -1377,8 +1403,14 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLiveTest do
              )
 
       view
-      |> element("#select_existing_sub_modal #text-search-input")
-      |> render_hook("text_search_change", %{value: "testing"})
+      |> element("#select_existing_sub_modal-filters")
+      |> render_change(%{"query" => "testing"})
+
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal-results-status",
+               "1 sub-objective available."
+             )
 
       assert has_element?(
                view,
@@ -1448,6 +1480,10 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLiveTest do
 
       assert has_element?(view, ".collapse", "#{title}")
 
+      assert Enum.any?(ObjectiveEditor.fetch_objective_mappings(project), fn mapping ->
+               mapping.revision.title == title
+             end)
+
       wait_for_coverage(view)
     end
 
@@ -1496,11 +1532,8 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLiveTest do
       wait_for_coverage(view)
     end
 
-    test "remove sub objective with one parent", %{
-      conn: conn,
-      project: project,
-      publication: publication
-    } do
+    test "final association requires confirmation, can be canceled, and is deleted only on confirmation",
+         %{conn: conn, project: project, publication: publication} do
       {:ok, sub_obj} = create_objective(project, publication, "sub_obj", "Sub Objective")
 
       {:ok, obj} =
@@ -1508,43 +1541,75 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLiveTest do
 
       {:ok, view, _html} = live(conn, live_view_route(project.slug, %{selected: obj.slug}))
 
-      assert has_element?(view, "##{obj.slug}")
-      assert has_element?(view, ".collapse", "#{sub_obj.title}")
+      refute has_element?(
+               view,
+               "button[phx-click='detach_sub_objective'][phx-value-slug=#{sub_obj.slug}]"
+             )
+
+      assert has_element?(
+               view,
+               "#delete-objective-action-#{obj.resource_id}[phx-hook='GlobalTooltip'][data-tooltip='Delete Learning Objective']"
+             )
+
+      assert has_element?(
+               view,
+               "#sub-objective-action-#{obj.resource_id}-#{sub_obj.resource_id}[phx-hook='GlobalTooltip'][data-tooltip='Delete sub-objective']"
+             )
 
       view
       |> element(
         "button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}]"
       )
-      |> render_click(%{"slug" => sub_obj.slug, "parent_slug" => obj.slug})
+      |> render_click()
 
-      assert has_element?(view, "#delete_sub_objective_modal", "Delete Sub-Objective")
-      assert has_element?(view, "#delete_sub_objective_modal", "#{sub_obj.title}")
+      assert has_element?(view, "#delete_sub_objective_modal", sub_obj.title)
+      assert has_element?(view, "#delete_sub_objective_modal", "final association")
+      assert has_element?(view, "#delete_sub_objective_modal", "This action cannot be undone")
 
-      view
-      |> element("button[phx-click='delete_sub_objective'][phx-value-slug=#{sub_obj.slug}]")
-      |> render_click(%{"slug" => sub_obj.slug, "parent_slug" => obj.slug})
+      assert has_element?(
+               view,
+               "#delete_sub_objective_modal #cancel-sub-objective-delete[autofocus]"
+             )
 
-      assert has_element?(view, ".collapse .line-through", "#{sub_obj.title}")
+      refute AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
 
-      wait_until(fn ->
-        has_element?(view, ~s{div[role="alert"].alert-info}, "Objective successfully removed")
-      end)
+      render_hook(view, "phx_modal.unmount", %{})
+      refute has_element?(view, "#delete_sub_objective_modal")
+      refute AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
 
-      assert 1 ==
-               project
-               |> ObjectiveEditor.fetch_objective_mappings()
-               |> length()
+      assert sub_obj.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               obj.resource_id
+             ).children
 
-      refute has_element?(view, ".collapse", "#{sub_obj.title}")
+      view
+      |> element(
+        "button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}]"
+      )
+      |> render_click()
 
-      wait_for_coverage(view)
+      view
+      |> element("button[phx-click='delete_sub_objective'][phx-value-slug=#{sub_obj.slug}]")
+      |> render_click()
+
+      render_async(view)
+      assert has_element?(view, ~s{div[role="alert"].alert-info}, "Sub-objective deleted")
+      assert AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
+      assert AuthoringResolver.from_resource_id(project.slug, obj.resource_id).children == []
+      assert length(ObjectiveEditor.fetch_objective_mappings(project)) == 1
+      refute has_element?(view, "##{sub_obj.slug}")
+
+      view
+      |> element("button[phx-click='display_add_existing_sub_modal'][phx-value-slug=#{obj.slug}]")
+      |> render_click()
+
+      refute has_element?(view, "#existing-sub-objective-#{sub_obj.resource_id}")
+      refute has_element?(view, "#select_existing_sub_modal-status")
+      refute has_element?(view, "#select_existing_sub_modal button", "Delete")
     end
 
-    test "remove sub objective with more than one parent", %{
-      conn: conn,
-      project: project,
-      publication: publication
-    } do
+    test "shared unlink preserves course content and other parents and updates the remaining action",
+         %{conn: conn, project: project, publication: publication} do
       {:ok, sub_obj} = create_objective(project, publication, "sub_obj", "Sub Objective")
 
       {:ok, obj_a} =
@@ -1553,47 +1618,191 @@ defmodule OliWeb.Workspaces.CourseAuthor.ObjectivesLiveTest do
       {:ok, obj_b} =
         create_objective(project, publication, "obj_b", "Objective B", [sub_obj.resource_id])
 
-      {:ok, view, _html} = live(conn, live_view_route(project.slug, %{selected: obj_a.slug}))
+      {:ok, page} = create_page_with_objective(project, publication, [sub_obj.resource_id])
+
+      {:ok, view, _html} =
+        live(
+          conn,
+          live_view_route(project.slug, %{expanded: Enum.join([obj_a.slug, obj_b.slug], ",")})
+        )
+
+      assert has_element?(
+               view,
+               "#sub-objective-action-#{obj_a.resource_id}-#{sub_obj.resource_id}[phx-hook='GlobalTooltip'][data-tooltip='Detach from learning objective']"
+             )
 
-      assert has_element?(view, "##{obj_a.slug}")
-      assert has_element?(view, "##{obj_b.slug}")
-      assert has_element?(view, "##{obj_a.slug} .collapse", "#{sub_obj.title}")
+      refute has_element?(
+               view,
+               "button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}]"
+             )
 
       view
-      |> element("button[phx-click='toggle_objective'][phx-value-slug=#{obj_b.slug}]")
-      |> render_click(%{"slug" => obj_b.slug})
+      |> element(
+        "##{obj_a.slug} button[phx-click='detach_sub_objective'][phx-value-slug=#{sub_obj.slug}]"
+      )
+      |> render_click()
+
+      render_async(view)
+      assert has_element?(view, ~s{div[role="alert"].alert-info}, "Sub-objective detached")
+      assert length(ObjectiveEditor.fetch_objective_mappings(project)) == 3
+      refute AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
+
+      assert AuthoringResolver.from_resource_id(project.slug, page.resource_id).objectives ==
+               page.objectives
+
+      assert AuthoringResolver.from_resource_id(project.slug, obj_a.resource_id).children == []
+
+      assert sub_obj.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               obj_b.resource_id
+             ).children
+
+      assert has_element?(
+               view,
+               "##{obj_b.slug} button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}]"
+             )
+
+      view
+      |> element("##{obj_a.slug} button[phx-click='display_add_existing_sub_modal']")
+      |> render_click()
+
+      assert has_element?(view, "#existing-sub-objective-#{sub_obj.resource_id}", sub_obj.title)
+
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal button[phx-click='add_existing_sub'][class~='h-8'][class~='border-Border-border-bold']"
+             )
+
+      refute has_element?(view, "#select_existing_sub_modal button", "Delete")
+
+      view
+      |> element("#select_existing_sub_modal-filters")
+      |> render_submit(%{"query" => "not found"})
+
+      assert has_element?(view, "#select_existing_sub_modal-empty")
+
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal-results-status[role='status'][aria-live='polite']",
+               "No sub-objectives match these filters."
+             )
+
+      view
+      |> element("#select_existing_sub_modal-filters")
+      |> render_submit(%{"query" => "Sub Objective"})
+
+      assert has_element?(view, "#existing-sub-objective-#{sub_obj.resource_id}")
+
+      assert has_element?(
+               view,
+               "#select_existing_sub_modal-results-status",
+               "1 sub-objective available."
+             )
+    end
 
-      assert has_element?(view, "##{obj_b.slug} .collapse", "#{sub_obj.title}")
+    test "tagged final association cannot be deleted or detached",
+         %{conn: conn, project: project, publication: publication} do
+      {:ok, sub_obj} = create_objective(project, publication, "sub_obj", "Sub Objective")
+
+      {:ok, obj} =
+        create_objective(project, publication, "obj", "Objective", [sub_obj.resource_id])
+
+      {:ok, _page} = create_page_with_objective(project, publication, [sub_obj.resource_id])
+      {:ok, view, _html} = live(conn, live_view_route(project.slug, %{selected: obj.slug}))
 
       view
       |> element(
-        "button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}][phx-value-parent_slug=#{obj_a.slug}]"
+        "button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}]"
       )
-      |> render_click(%{"slug" => sub_obj.slug, "parent_slug" => obj_a.slug})
+      |> render_click()
+
+      refute has_element?(view, "#delete_sub_objective_modal")
+      assert has_element?(view, ~s{div[role="alert"].alert-danger}, "tagged to course content")
 
-      assert has_element?(view, "#delete_sub_objective_modal", "Delete Sub-Objective")
+      render_hook(view, "delete", %{"slug" => sub_obj.slug})
+      refute AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
+
+      render_hook(view, "detach_sub_objective", %{
+        "slug" => sub_obj.slug,
+        "parent_slug" => obj.slug
+      })
+
+      render_async(view)
+      assert has_element?(view, ~s{div[role="alert"].alert-danger}, "final association")
+      refute AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
+
+      assert sub_obj.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               obj.resource_id
+             ).children
+    end
+
+    test "confirmation rechecks whether another parent was added",
+         %{conn: conn, project: project, publication: publication} do
+      {:ok, sub_obj} = create_objective(project, publication, "sub_obj", "Sub Objective")
+
+      {:ok, obj} =
+        create_objective(project, publication, "obj", "Objective", [sub_obj.resource_id])
+
+      {:ok, view, _html} = live(conn, live_view_route(project.slug, %{selected: obj.slug}))
 
       view
       |> element(
-        "button[phx-click='delete_sub_objective'][phx-value-slug=#{sub_obj.slug}][phx-value-parent_slug=#{obj_a.slug}]"
+        "button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}]"
       )
-      |> render_click(%{"slug" => sub_obj.slug, "parent_slug" => obj_a.slug})
+      |> render_click()
 
-      assert has_element?(view, "##{obj_a.slug} .line-through", "#{sub_obj.title}")
+      {:ok, other_parent} =
+        create_objective(project, publication, "other", "Other Objective", [sub_obj.resource_id])
 
-      wait_until(fn ->
-        has_element?(view, ~s{div[role="alert"].alert-info}, "Objective successfully removed")
-      end)
+      view |> element("button[phx-click='delete_sub_objective']") |> render_click()
+      render_async(view)
 
-      assert 3 ==
-               project
-               |> ObjectiveEditor.fetch_objective_mappings()
-               |> length()
+      assert has_element?(
+               view,
+               ~s{div[role="alert"].alert-danger},
+               "other learning-objective associations"
+             )
 
-      refute has_element?(view, "##{obj_a.slug} .collapse", "#{sub_obj.title}")
-      assert has_element?(view, "##{obj_b.slug} .collapse", "#{sub_obj.title}")
+      refute AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
 
-      wait_for_coverage(view)
+      assert sub_obj.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               obj.resource_id
+             ).children
+
+      assert sub_obj.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               other_parent.resource_id
+             ).children
+    end
+
+    test "confirmation rechecks whether course content was tagged",
+         %{conn: conn, project: project, publication: publication} do
+      {:ok, sub_obj} = create_objective(project, publication, "sub_obj", "Sub Objective")
+
+      {:ok, obj} =
+        create_objective(project, publication, "obj", "Objective", [sub_obj.resource_id])
+
+      {:ok, view, _html} = live(conn, live_view_route(project.slug, %{selected: obj.slug}))
+
+      view
+      |> element(
+        "button[phx-click='display_sub_objective_delete_modal'][phx-value-slug=#{sub_obj.slug}]"
+      )
+      |> render_click()
+
+      {:ok, _page} = create_page_with_objective(project, publication, [sub_obj.resource_id])
+      view |> element("button[phx-click='delete_sub_objective']") |> render_click()
+      render_async(view)
+
+      assert has_element?(view, ~s{div[role="alert"].alert-danger}, "tagged to course content")
+      refute AuthoringResolver.from_resource_id(project.slug, sub_obj.resource_id).deleted
+
+      assert sub_obj.resource_id in AuthoringResolver.from_resource_id(
+               project.slug,
+               obj.resource_id
+             ).children
     end
 
     test "renders links to revision history if #show_links is added to the url (being an admin)",
diff --git a/test/scenarios/directives/objectives_handler_test.exs b/test/scenarios/directives/objectives_handler_test.exs
index c2cb159fe94..cd30e1791f9 100644
--- a/test/scenarios/directives/objectives_handler_test.exs
+++ b/test/scenarios/directives/objectives_handler_test.exs
@@ -45,6 +45,7 @@ defmodule Oli.Scenarios.Directives.ObjectivesHandlerTest do
 
     assert child.resource_id in parent.children
     refute removed_child.resource_id in parent.children
+    assert removed_child.deleted
   end
 
   test "objectives directive reports missing parents" do