Changing the parent item of a sequence diagram
• In the Packages pane, drag the Sequence Diagram to the item that you want to own the diagram.
Alternatively,
1. In an appropriate pane, locate the item you want to be the parent of the Sequence Diagram.
2. Open the Sequence Diagram, ensuring that you can see the top left corner.
3. From an appropriate pane, drag the item you want to be parent to the top left corner of the Sequence Diagram.