As the 3rd mother here of a daughter I concur with Mig and TIS. If they don't respect the parents enough to at least come to the door and say hi how much respect are they gonna show your daughter. I never had the problem with my daughter. She knows I give her enough space to make her decisions because I feel there should be mutual respect between parent and child. She also knows if she did anything stupid I'd kick her ass.

BTW...I don't care how legal it is if some 20 year old asked my daughter to drink when she was 17 he'll be doing all his eating through a feeding tube.