Shape binder is what you need. Shape binder can be used to reference geometry from another body. What I would do is I’d make one pocket on the main body. Then select another body and make it an active body. Then select the pocket you made (the surface or the edge) and create a shape binder (part design). This will effectively import the selected feature from the first body and you can reference it from second body. Make sure you hide the first body, as it somehow gets in the way of shape binder, for some reason. Repeat for third body.