diff --git a/ee/lib/ee/gitlab/quick_actions/epic_actions.rb b/ee/lib/ee/gitlab/quick_actions/epic_actions.rb
index 30e7d5a7dddec2c0aeedb197475a191a83d0ea61..06de0c366533b02dcab0ea8e3f2785e56d848ede 100644
--- a/ee/lib/ee/gitlab/quick_actions/epic_actions.rb
+++ b/ee/lib/ee/gitlab/quick_actions/epic_actions.rb
@@ -15,12 +15,20 @@ module EpicActions
             _("Adds %{epic_ref} as child epic.") % { epic_ref: child_epic.to_reference(quick_action_target) } if child_epic
           end
           types Epic
-          condition { action_allowed? }
+          condition { can_admin_relation? }
           params '<&epic | group&epic | Epic URL>'
           command :child_epic do |epic_param|
             child_epic = extract_epic(epic_param)
+            child_error = validate_update(quick_action_target, child_epic, :child)
 
-            @execution_message[:child_epic] = set_child_epic_update(quick_action_target, child_epic)
+            @execution_message[:child_epic] =
+              if child_error.present?
+                child_error
+              else
+                @updates[:quick_action_assign_child_epic] = child_epic
+
+                success_set_message(quick_action_target, child_epic, :child)
+              end
           end
 
           desc { _('Remove child epic from an epic') }
@@ -34,14 +42,15 @@ module EpicActions
           params '<&epic | group&epic | Epic URL>'
           command :remove_child_epic do |epic_param|
             child_epic = extract_epic(epic_param)
+            child_error = validate_removal(quick_action_target, child_epic, :child)
 
             @execution_message[:remove_child_epic] =
-              if child_epic && quick_action_target.child?(child_epic.id)
+              if child_error.present?
+                child_error
+              else
                 Epics::EpicLinks::DestroyService.new(child_epic, current_user).execute
 
-                _("Removed %{epic_ref} from child epics.") % { epic_ref: child_epic.to_reference(quick_action_target) }
-              else
-                _("Child epic does not exist.")
+                success_remove_message(quick_action_target, child_epic, :child)
               end
           end
 
@@ -52,12 +61,20 @@ module EpicActions
             _("Sets %{epic_ref} as parent epic.") % { epic_ref: parent_epic.to_reference(quick_action_target) } if parent_epic
           end
           types Epic
-          condition { action_allowed? }
+          condition { can_admin_relation? }
           params '<&epic | group&epic | Epic URL>'
           command :parent_epic do |epic_param|
             parent_epic = extract_epic(epic_param)
+            parent_error = validate_update(quick_action_target, parent_epic, :parent)
 
-            @execution_message[:parent_epic] = set_parent_epic_update(quick_action_target, parent_epic)
+            @execution_message[:parent_epic] =
+              if parent_error.present?
+                parent_error
+              else
+                @updates[:quick_action_assign_to_parent_epic] = parent_epic
+
+                success_set_message(quick_action_target, parent_epic, :parent)
+              end
           end
 
           desc { _('Remove parent epic from an epic') }
@@ -70,14 +87,15 @@ module EpicActions
           condition { action_allowed_only_on_update? }
           command :remove_parent_epic do
             parent_epic = quick_action_target.parent
+            parent_error = validate_removal(quick_action_target, parent_epic, :parent)
 
             @execution_message[:remove_parent_epic] =
-              if parent_epic
-                Epics::EpicLinks::DestroyService.new(quick_action_target, current_user).execute
-
-                _('Removed parent epic %{epic_ref}.') % { epic_ref: parent_epic.to_reference(quick_action_target) }
+              if parent_error.present?
+                parent_error
               else
-                _("Parent epic is not present.")
+                Epics::EpicLinks::DestroyService.new(parent_epic, current_user).execute
+
+                success_remove_message(quick_action_target, parent_epic, :parent)
               end
           end
 
@@ -89,58 +107,64 @@ def extract_epic(params)
             extract_references(params, :epic).first
           end
 
-          def action_allowed?
-            quick_action_target.group&.feature_available?(:subepics) &&
-              current_user.can?(:"admin_#{quick_action_target.to_ability_name}", quick_action_target)
+          def can_admin_relation?(epic = quick_action_target)
+            current_user.can?(:admin_epic_tree_relation, epic)
           end
 
           def action_allowed_only_on_update?
-            quick_action_target.persisted? && action_allowed?
+            quick_action_target.persisted? && can_admin_relation?
           end
 
           def epics_related?(epic, target_epic)
             epic.child?(target_epic.id) || target_epic.child?(epic.id)
           end
 
-          def set_child_epic_update(target_epic, child_epic)
-            return child_error_message(:not_present) unless child_epic.present?
-            return child_error_message(:already_related) if epics_related?(child_epic, target_epic)
-            return child_error_message(:no_permission) unless current_user.can?(:read_epic, child_epic)
-
-            @updates[:quick_action_assign_child_epic] = child_epic
+          def validate_update(target_epic, epic, type)
+            return error_message(:does_not_exist, type) unless epic.present?
+            return error_message(:already_related, type) if epics_related?(epic, target_epic)
 
-            _("Added %{epic_ref} as a child epic.") % { epic_ref: child_epic.to_reference(target_epic) }
+            error_message(:no_permission, type) unless can_admin_relation?(epic)
           end
 
-          def set_parent_epic_update(target_epic, parent_epic)
-            return parent_error_message(:not_present) unless parent_epic.present?
-            return parent_error_message(:already_related) if epics_related?(parent_epic, target_epic)
-            return parent_error_message(:no_permission) unless current_user.can?(:read_epic, parent_epic)
+          def validate_removal(target_epic, epic, type)
+            return error_message(:not_present, type) unless epic.present?
+            return error_message(:does_not_exist, type) if type == :child && !target_epic.child?(epic.id)
 
-            @updates[:quick_action_assign_to_parent_epic] = parent_epic
-
-            _("Set %{epic_ref} as the parent epic.") % { epic_ref: parent_epic.to_reference(target_epic) }
+            error_message(:no_permission, type) unless can_admin_relation?(epic)
           end
 
-          def parent_error_message(reason)
+          def error_message(reason, relation)
             case reason
+            when :does_not_exist
+              _('%{relation_type} epic does not exist.') % { relation_type: relation.to_s.capitalize }
             when :not_present
-              _("Parent epic doesn't exist.")
+              _('%{relation_type} epic is not present.') % { relation_type: relation.to_s.capitalize }
             when :already_related
-              _("Given epic is already related to this epic.")
+              _('Given epic is already related to this epic.')
             when :no_permission
               _("You don't have sufficient permission to perform this action.")
             end
           end
 
-          def child_error_message(reason)
-            case reason
-            when :not_present
-              _("Child epic doesn't exist.")
-            when :already_related
-              _("Given epic is already related to this epic.")
-            when :no_permission
-              _("You don't have sufficient permission to perform this action.")
+          def success_set_message(target_epic, epic, relation)
+            reference = epic.to_reference(target_epic)
+
+            case relation
+            when :child
+              _('Added %{epic_ref} as a child epic.') % { epic_ref: reference }
+            when :parent
+              _('Set %{epic_ref} as the parent epic.') % { epic_ref: reference }
+            end
+          end
+
+          def success_remove_message(target_epic, epic, relation)
+            reference = epic.to_reference(target_epic)
+
+            case relation
+            when :child
+              _('Removed %{epic_ref} from child epics.') % { epic_ref: reference }
+            when :parent
+              _('Removed parent epic %{epic_ref}.') % { epic_ref: reference }
             end
           end
         end
diff --git a/ee/spec/services/quick_actions/interpret_service_spec.rb b/ee/spec/services/quick_actions/interpret_service_spec.rb
index 28f86bf37f4c4c04e84461ad245e7a59de73c56c..1764c34911cb0ef0b4ee2876f17b9380a65115d8 100644
--- a/ee/spec/services/quick_actions/interpret_service_spec.rb
+++ b/ee/spec/services/quick_actions/interpret_service_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-RSpec.describe QuickActions::InterpretService do
+RSpec.describe QuickActions::InterpretService, feature_category: :team_planning do
   let(:current_user) { create(:user) }
   let(:developer) { create(:user) }
   let(:developer2) { create(:user) }
@@ -691,7 +691,7 @@
       let(:referenced_epic) { create(:epic, group: epic.group) }
 
       before do
-        group.add_developer(current_user)
+        group.add_guest(current_user)
         stub_licensed_features(epics: true, subepics: true)
       end
 
@@ -727,8 +727,8 @@
 
         context 'when a user has permissions to add epic relations' do
           before do
-            group.add_developer(current_user)
-            another_group.add_developer(current_user)
+            group.add_guest(current_user)
+            another_group.add_guest(current_user)
           end
 
           it_behaves_like 'adds quick action parameter', :quick_action_assign_child_epic, :child_epic
@@ -952,7 +952,7 @@
       context 'when subepics are disabled' do
         before do
           stub_licensed_features(epics: true, subepics: false)
-          group.add_developer(current_user)
+          group.add_guest(current_user)
         end
 
         it_behaves_like 'epic relation is not removed' do
@@ -1481,12 +1481,14 @@
     end
 
     context 'epic commands' do
+      let(:other_group) { create(:group, :private) }
       let(:epic) { create(:epic, group: group) }
-      let(:epic2) { create(:epic, group: group) }
+      let(:epic2) { create(:epic, group: other_group) }
 
       before do
         stub_licensed_features(epics: true, subepics: true)
-        group.add_developer(current_user)
+        group.add_guest(current_user)
+        other_group.add_guest(current_user)
       end
 
       shared_examples 'target epic does not exist' do |relation|
@@ -1494,7 +1496,7 @@
           _, _, message = service.execute(content, epic)
 
           expect(message)
-            .to eq("#{relation.capitalize} epic doesn't exist.")
+            .to eq("#{relation.capitalize} epic does not exist.")
         end
       end
 
@@ -1508,6 +1510,13 @@
       end
 
       shared_examples 'without permissions for action' do
+        before do
+          allow(current_user).to receive(:can?).with(:use_quick_actions).and_return(true)
+          allow(current_user).to receive(:can?).with(:admin_all_resources).and_return(true)
+          allow(current_user).to receive(:can?).with(:admin_epic_tree_relation, epic).and_return(true)
+          allow(current_user).to receive(:can?).with(:admin_epic_tree_relation, epic2).and_return(false)
+        end
+
         it 'returns unsuccessful execution message' do
           _, _, message = service.execute(content, epic)
 
@@ -1545,15 +1554,9 @@
           it_behaves_like 'target epic does not exist', :child
         end
 
-        context 'when user has no permission to read epic' do
+        context 'when user has no permissions to relate the child epic' do
           let(:content) { "/child_epic #{epic2&.to_reference(epic)}" }
 
-          before do
-            allow(current_user).to receive(:can?).with(:use_quick_actions).and_return(true)
-            allow(current_user).to receive(:can?).with(:admin_epic, epic).and_return(true)
-            allow(current_user).to receive(:can?).with(:read_epic, epic2).and_return(false)
-          end
-
           it_behaves_like 'without permissions for action'
         end
       end
@@ -1581,7 +1584,7 @@
         end
 
         context 'when epic reference is wrong' do
-          let(:content) { "/child_epic qwe" }
+          let(:content) { "/remove_child_epic qwe" }
 
           it 'returns empty explain message' do
             _, explanations = service.explain(content, epic)
@@ -1603,6 +1606,16 @@
               .to eq("Child epic does not exist.")
           end
         end
+
+        context 'when user has no permissions to remove child epic' do
+          let(:content) { "/remove_child_epic #{epic2&.to_reference(epic)}" }
+
+          before do
+            epic2.update!(parent: epic)
+          end
+
+          it_behaves_like 'without permissions for action'
+        end
       end
 
       context 'parent_epic command' do
@@ -1636,15 +1649,9 @@
           it_behaves_like 'target epic does not exist', :parent
         end
 
-        context 'when user has no permission to read epic' do
+        context 'when user has no permissions to relate the parent epic' do
           let(:content) { "/parent_epic #{epic2&.to_reference(epic)}" }
 
-          before do
-            allow(current_user).to receive(:can?).with(:use_quick_actions).and_return(true)
-            allow(current_user).to receive(:can?).with(:admin_epic, epic).and_return(true)
-            allow(current_user).to receive(:can?).with(:read_epic, epic2).and_return(false)
-          end
-
           it_behaves_like 'without permissions for action'
         end
       end
@@ -1693,6 +1700,16 @@
               .to eq("Parent epic is not present.")
           end
         end
+
+        context 'when user has no permissions to remove parent epic' do
+          let(:content) { "/remove_parent_epic" }
+
+          before do
+            epic.parent = epic2
+          end
+
+          it_behaves_like 'without permissions for action'
+        end
       end
     end
   end
diff --git a/locale/gitlab.pot b/locale/gitlab.pot
index e23a5239d78872d49e61d9f2e5c47e620445e5b5..d5224f8dc06ccf0920510f849e5db833d2f2507d 100644
--- a/locale/gitlab.pot
+++ b/locale/gitlab.pot
@@ -953,6 +953,12 @@ msgstr ""
 msgid "%{ref} cannot be added: %{error}"
 msgstr ""
 
+msgid "%{relation_type} epic does not exist."
+msgstr ""
+
+msgid "%{relation_type} epic is not present."
+msgstr ""
+
 msgid "%{releases} release"
 msgid_plural "%{releases} releases"
 msgstr[0] ""
@@ -8469,12 +8475,6 @@ msgstr ""
 msgid "Child epic"
 msgstr ""
 
-msgid "Child epic does not exist."
-msgstr ""
-
-msgid "Child epic doesn't exist."
-msgstr ""
-
 msgid "Child issues and epics"
 msgstr ""
 
@@ -29743,12 +29743,6 @@ msgstr ""
 msgid "Parent"
 msgstr ""
 
-msgid "Parent epic doesn't exist."
-msgstr ""
-
-msgid "Parent epic is not present."
-msgstr ""
-
 msgid "Parsing error for param :embed_json. %{message}"
 msgstr ""