I would focus on teaching your daughter how to handle the situation. Explain to her that she cannot be all things. While she may not be the fastest , she is sure to be the toughest on defense. Teach her how to laugh off or blow off the comments (even if she doesn't feel that way). These other girls are only saying because it effects her and makes them feel better in some unconscious way. Forget the other mother. If she doesn't see an issue now, then she won't. But you can bet if it were me and said in my presense or when the girls were at my house, it is my right to correct the situation verbally. Explaining to the two girls that not everyone will be the best at everything etc. etc. You need to turn the extra weight or muscle on your daughter into an asset. If she believes that then she will better defend her position against these girls. I was an athlete when I was younger and went thru similar situations. I feel my father prepared me to cope with this kind of petty critisism. Unfortunatley this will continue. Kids are that way and there will always be the "mean" girls. The way your daughter handles the situation will be the difference.