There are certain actions I've tried animate, such as a shotgun pump-action motion, which are dependent on coordination between layers in different groups (where in the case of the character [I hid her head because it partially obscures the gun - chibi design and all that, y'know] below, her left hand is on the pump of the shotgun, and in the same layer as the shotgun, which is above her left arm).

I can't think of any ways to anchor the pump to the gun and the hand to the pump and wrist. How can I coordinate that better, so the hand actually aligns with both the shotgun's pump and her forearm as the three parts move in sync?