It's not worth the stress to deal with a family who doesn't follow your policies.
Tom Copeland's 3 choices of life:
1. You're happy the way thing are - let the parents do whatever they want.
2. You're not happy - tell the parents what they need to change.
3. You're not happy and won't confront the parents - quit.
http://tomcopelandblog.com/three-choices-life