Here is my opinion on this, take it or leave it.
In all honesty at the 10U level I agree with the parents. There is no way that a child that age should be put in the position of having to choose a sport. Encourage them to play as many sports as possible to help their overall athletic ability. There is plenty of time later to focus on just one. I think that at 10U the goals should be less about winning( which is the impression I get from your answer to the parents, sorry if I am taking that wrong) and more about teaching the girls fundamentals as much time as they are able to commit, as well as helping them develop a love for the game.
A little side story here, sorry if it gets long winded. My daughter at 10U and 11U(she is now a freshman playing in college) played for a team that did not win many games, but the coach let everybody have a chance and play multiple positions. She left him after 11U to seek a different level. But when she was fortunate to be chosen HM All-Ohio as a freshman, that coach was one of the first people she wanted to call and thank because he taught her to love the game. 10U and 12U coaches please keep this in mind. I believe that no player who does not develop a deep love for the game will pay the price and do the work to play at the collegiate level. Don't take that away from kids just so some trophies can be won.