'Containment' can be assigned within a 'Package Diagram' via drag-and-drop. Both the "to-be" parent and child 'Package' constructs must be added to the diagram first, before containment can be assigned.

1. Within a 'Package Diagram,' select the 'Package' construct you would like to assign as the parent.
2. Click the green circle and continue to hold down the left mouse button.
3. Drag the green circle over to the child 'Package' of your choice.
4. When the child 'Package' box highlights green, release the left mouse button over the 'containment' section to add a decomposed by relationship.
5. Once added to the diagram, the new relationship should appear as a circle with a plus sign, with a solid line from the parent to the child 'Package' construct.
6. Click the 'Save' button located on the toolbar to persist your changes to your project's database.