I have no problem with girls playing multiple sports and I will work around their schedules during our "off-season."
However, rec softball is not another sport and if you miss one of my practices to go to another softball anything, your butt will be on the bench doing spray charts all weekend. You do "other" softball things (hitting coaches, pitching coaches, etc.) on your own time, not mine.
If you do it twice, I really hope you like your like your rec team because until you can find another travel team, that's all you're going to have.
To me, if you still have a pull toward rec, you really aren't ready to be on my team, anyway. Missing anything on my team for anything rec shows a lack of commitment that simply will not be tolerated by me, my assistants or your teammates and their families.
Seems a bit much for a 10U team.