Don't be their friend and don't be their parent. We often forget both of those. Be a mentor. Be a role model. Be a counselor. Let the parents be parents, whether you like how they parent or not, and you be their band director. I have decades of experience in the classroom and once I had my child I figured out real quick to parent my own and let others parent theirs. And while we often want to claim how many kids don't have parents at home I believe we exaggerate that out of wanting to feel important. When you are 23 and just trying to figure out how to teach and working on getting your own life and finances and relationships in order, trying to parent a 13 year old is probably a little much for you right then and there.