GGU-STABILITY: "Duplicate" menu item
You can duplicate an existing slip body, in order to use it as the basis for editing.

Click on the button of the slip body to be duplicated. The slip body is then represented in the system and can be modified to suit your needs by moving the polygon points using the mouse. Then press the [Return] key to accept the new slip body and confirm the "Use slip body?" query with "Yes".