Yes. You will be asked at the door to supply proof of kinship in the form of driver licenses. Then during the evening, they must be with you at all times - including trips to the restrooms. And they are never allowed in the designated bar area (inside the railing). We welcome under 21 designated drivers too. But by law, someone in the party must be 25 years or older.
Please don't make the mistake of "slipping" them a drink, 'cause you're their parent or buddy. We (and our attorneys) take our responsibility to abide by Pennsylvania law very seriously.