I know the other schools might be a bit ****ty, but gee, it sounds like the school she is at is actively going out of their way to not include her, and that is NOT cool at all. Personally, I wouldn't waste my breath saying anything to them as it's only going to go one and way not the way you want it too Is she upset by this or is she just happy that she's going for something else? Maybe just focus on that for now and next year make a point of being more involved in the carnival so you can try to stop it happening again.