good thought apples, I have actually gone so far as to type up a reminder on certain issues before and had the stack at the door (for show ) and only given it to the "trouble" family to sign. Just made it look like a all around note to all, that way the one family didn't feel too singled out, but I still got the point across.
HAHAHA, I've done that! I have cubbies for all parents. I've put memos in all cubbies before one specific parent came so it looked liked everyone was getting it. LOL Then I'd take them out and throw them the min they left. Tooooo funny.