I have similar frustrations with sports conflicts. I've become very strict on this, and have worked it out with coaches. I expect kids to split the difference. My soccer kids skip band 1/week and go to soccer, they skip soccer 1/week and go to band. Football boys leave early from football and that gets them to marching band late. If the kids don't respect that arrangement then they lose points on their grade (unexcused absences from rehearsal) and might lose their marching spot to an alternate. Sometimes coaches are jerks about it and I have to involve administration to ensure it doesn't hurt their playing time.

I've lost some kids due to this. It's addition by subtraction. I'll take fewer kids with better work ethic and dedication every time. The kids who only show up when they want to can go play football instead.