M.D.
Personally, I would not drop my child off and not stay. I don't expect to be included in the party or for the parents to pay for anything for me. That is just my own comfort level. I always stay and offer to help where ever needed, if not needed I just stay out of the way, with eyes on my kid. My theory is that "things" happen even with the best of intentions. Now that my child is 8 I would be more willing to consider it possibly but definitely not at 6. Again that is just me.