Whenever pastor's kids are the primary musicians, you are already defeated. I am a PK and have served in churches with this problem. I will tell you that you have to value your calling. At the end of the day, your calling is what you are responsible for. If this cannot work with who you are, step away from the music thing until they are willing to make changes. You must guard your heart from resentment, and sometimes that means stepping down to move up.