Of course. you have to speak up.

use a firm and respectful tone.
even if the coach explains why your daughter should play defense, say you aggree with her ,just say:" you probably is right. But I would like her to try differnt positions. so how about  50/50? I would really appreciate your effort of being accomodating...." make her agree that she will try. if she does not do it, talk to her or him again until the she/he does so. you pay the money, at this level, you certainly have a right to ask..
My son plays in a AAA team ranks national top20. our coach is a professional coach. I really don't want my son to play at this level. but I am so fed up with parents coach. and even our coach who has a reputaion of being tough, parents still discuss with him about their sons' position.
good luck.