I get your frustration because my husband used to coach our daughter's softball team from from 9u - 12u and I know its tough setting up practices trying to accommodate the widest attendance, and having 4-5 girls miss for AAU or JO and getting frustrated because as a coach, you still want to make sure the girls are developing as players and gelling as a team.
BUT Sometimes you just have to hit the reset button and realize that try as you might, there is little you can do ...so try not to let it frustrate you.
My daughter is an 8th grader and has played three sports year round since she was 5. At 10u, she played $occer, winter basketball leagues, softball for OGSO, and travel softball. Now that she is in middle school, she plays volleyball, basketball and softball for the school in addition to year round travel softball.
She is also a pitcher, and works on pitching 3-4 times per week mixing in lessons every other week, takes weekly hitting lessons and on the days she doesn't pitch, she hits at home doing T work. She has practice for her travel team
1-2 days a week (usually fielding with Bob Hoiles during the week and then a weekend practice). This is in ADDITION to volleyball five days a week for the school, taking advanced classes, maintaining a 4.0 and mixing in some college camps here and there now that she is in 8th grade. I think it is absolutely crazy but SHE wouldn't have it any other way.
The point I'm trying to make is that when kids are younger, it is possible for them to play many different sports and play them all well. Now whether she will be able to keep up this schedule next year in high school is yet to be determined and that is a choice that SHE will have to make but there is NO WAY I would have made her make that choice at 10u.