If there's an arrangement with the parents, just communicate that. That doesn't sound like it's the case here though. We had a girl on our last team who missed a lot of weeknights because of distance. Other parents all knew why and it was not a big deal at all. Ditto on other sports commitments. Just say so and spare the team the drama. I swear 95%of team drama could be prevented by decent communication from coaches.
And I swear that 95% of team drama could be prevented by the parents minding their own business, and not trying to run the team. That's the coach's job...