I can pass on some advice my friend ran up against. Type yourself up a form stating the rules for the parents- include what time the kids need to be picked up by, tell them you will charge more money at that cut off time. Also, she ran into a problem of releasing the kids to the parents after they had been drinking. She then put in a clause that she would NOT release the child if the parent was obviously drunk.
at 10:59 PM on Jan. 6, 2011