Ok another reason for me to appreciate my little old Catholic school and parents. We never engaged in such nonsense as this. You were expected to get along with all your classmates or the nuns would get you. And if parents couldn't sign on to that well then the priests would be after them too.
Ember, I don't know why you are agreeing to this. The Principal is not showing good leadership abilities. If she/he wants to impose such edicts then it is their responsibility to carry it out, not yours. I'd much rather you stand up for the kids and tell the mom and principal to grow up.
Mind you we had issues of kids with disorders, bullies and all sorts of problems in our class. The teachers, parents and administrators all handled it the same. You were expected to get along and play nice. And if you couldn't play nice with anyone then you got yourself booted out of school. Usually it just took a trip to the principal's office (she was a nun) and a reminder of how naughty we were being to calm the wilder students. In Catholic School the highest authority was God, and trust me no kid wanted to tempt his wrath.