One way to alleviate this kind of anxiety is to remind her that the behavior of other kids is someone else's problem, not hers. In this case, the problem is the coach's. If the coach decides to address the problem, or ignore it, that's his choice.
This is kind of what I do. I tell my two that you can't control how other people act - but you CAN control how you react to it. Then we talk about how you need to save your energy for the important battles - the ones in which you can actually make a difference. You can choose to stay upset about something you can't change and end up stressed out, or you can let it go and save your energy for something you can change.
Sometimes it works... sometimes they just stay upset, lol. They're still young.
