Hi Crimson, about drop offs and your son. when my d was younger we did most swaps through daycare and school. i'd let my d know who was picking her up later so she knew who to expect. direct drop-offs were always a little rough.
when she was about 4 we had a conversation and she told me that she was always torn between being happy to see one of us while missing the other at the same time.
i think your son may be at this same stage.
"In a ham and eggs breakfast, the hen is involved, but the pig is committed".