Have a function to set up, need guidance

That one is a bit tricky. The fundamental rule is you cannot change things in front/behind other things when using a puppet. The only thing you can do is tricks like have two sets of arms, one in front, one behind the body. Then use a swapset or similar to show one arm or the other. But then you have to get the arm exactly lined up when swapping between them. You can try doing tricks like having an invisible forearm then attacking two other visible arms in front/behind the body. You drag the invisible arm and the others then follow. That can make dragging more consistent, but its a bit hacky. But if you want one arm that moves in front and behind, that is not likely to work. (Note: you could also have two bodies I guess instead - the normal one plus another copy in front of the arms that you can turn on with a trigger - so the arm is not really going behind the body - instead a new body (chest area?) appears in front of the arms making it look like the arms went behind the body.