Reacting after the fact is always a problem.
You need to be proactive, and sit down with parents, students, and mentors, and flesh out a basic team structure. After that, you need to define responsibilities for each position, and a method of bringing greivances to the mentor's attention.
Hint: It should NEVER be a member's parent complaining to mentors unless there is a major issue or the mentors are ignoring student input. The interactions should be student to mentors, or student leadership to mentor.
The students need to be comfortable bringing complaints up to the mentors, and the mentors need to understand that their first task is to listen to the students and help them accomplish things, not be dictators. It's a hard paradigm to create. It took us 4-5 years to get everything in place, and we still struggle with balance every year.
Here is a somewhat outdated graph of our team structure:
http://www.fightingpi.org/Team%201718/Structure.shtml