Arms in front then back of head.

Not at a computer, so I cannot try the following, but if you want one swap set I would try the following. This assumes the head is independent and attached to the body, but a sibling of the body in the artwork.

Put one set of arms at the same level as the head and body before them, the other behind them. Put both sets of arms in a swapset.

- Character

- - +Arms in front of body

- - +Head

- - Body

- - +Arms behind body (hidden)

Both sets of arms go into a swap set. Both can attach to the body (if independent). The Head and Body layers do not go into the swap set.

Alternstively you can create two swap sets independently. Put a set of arms plus a blank layer in a sublayer together, which you turn into a swap set. So you are swapping between the arms and a blank layer. One swapset makes the blank layer the default, the other swapset makes the arms the default, The bind the same key to two different triggers for the two swap sets. You will see two things in the timeline because you are adjusting two swapsets - they just happen to use the same key trigger, This way you can put the arms anywhere you like in the puppet hierarchy.