As far as I know it is a legitimate travel organization (is there any way I can confirm this for sure).Is this a legit travel ball team that you're dealing with, or is it more of a town travel, girls-and-parents-all-know-each-other kind of situation? If new players just showed up and are getting much more playing time despite equal or lower skills and less commitment, it sounds to me like they're friends of the coach and/or his daughter. And that's okay -- early 10's need committed parents to coach, it's not an easy gig.
Just keep in mind that there may not be much your DD can do to crack the lineup if a subset of the team is going out together after games.
With that said, you also mentioned that your daughter tends to catch balls at her side, which is a big problem for a middle infielder. If you read through the threads here on DFP, a recurring theme is that you cannot leave your daughter's development to team coaches. They have a dozen or more girls to work with and limited time. If you can't get out and help your daughter develop outside of team practices, then find some local coaches or clinics who can.
We don't leave all of her development to the team. She had a batting coach for awhile to fix some things we didn't realize were broken and I take her out regularly and hit ground balls to her try to break her of fielding from the side.