Lawyer: I don’t see how “shleping” a sweater is more cumbersome than “shleping” various outfits for different times of the day, and changing outfits numerous times. We are discussing a school rule for a shabbaton where not all the girls come from wealthy homes and have 15 clothing stores at there disposal. Obviously you and your girls are entitled to wear as many outfits per day as you see fit. That goes for my girls as well.
However, at a shabbaton, the school is entitled to make the rules. and this particular rule was put in place for good reason.
see Mammele’s post above.