First of all, it's hard to respond to this without knowing a few details... but based off what you gave us to work with, if I were you, I would try my best to handle this myself, without involving my pastor/dad.
It may be time for you to have a come to Jesus meeting with them. Pray about the situation and the resolution. Then, at the next rehearsal, address the choir with your concerns and make it clear what you expect from them and what they can expect from you. Leave space for any questions or comments, and be prepared to openly and honestly address whatever their concerns are. But be sure to maintain control, otherwise it could turn into a shouting match or a "them against you" attack. And be sure to let them know that after this discussion, personal issues are not to be handled during rehearsal, but they can feel free to see you or contact you after or before rehearsal.
Basically, I think most of this can be resolved by you just being clear on what your expectations are of them, and then enforcing it. Be kind, be pleasant and respectful, be firm but easygoing, be ministry-minded, be about your business, and be consistent.
Most importantly, I would encourage you to keep something in mind that most people rarely consider: they may be right and you may be wrong. Just keep that in the back of your mind as you listen to their concerns.
