I'm not claiming she throws (4) pitches. I'm claiming she's working on (4) pitches. I don't consider any of them mastered and I never will. All I'm asking for is that she is able to continue working on the pitches she's been taught.
You ever watched a 12U girl that's been told she can't pitch, been pulled for the speedster numerous times, and lost games 23-1 because her infield is incompetent come off the field after striking someone out with her new toy(s)? I have. It's a face I'd like to see again over and over.
By disguise I mean she has a tendency to change her motion when she's not supposed to. Everything should be the same as her fastball except the way the throwing arm comes through, the wrist, and the release.
Still sounds like you are asking her to make up for sloppy defense with pitches that she is still "working on".
Sounds like she is really good at throwing strikes and hitting her spots with her FB, with does make her one-dimensional and hittable if the FB is not overpowering. She needs another go-to pitch that she is confident in, and can throw for strikes. At her age and size, it is not likely to be a drop or screwball (probably someday soon, but not yet), so IMO her best bet at this age is to "master" the CU. By "master" I mean she needs to disguise it well and throw it for strikes. A reasonably quick FB and a good CU will serve her very well at her level (but she still needs a defense behind her!!!)
Like I said earlier, keep her working on her movement pitches and ask the coach to work them in when there is an opportunity.
BTW...there is NOTHING sweeter for a pitcher than making a batter look silly with a 3-2 Change Up. I guarantee that will bring a smile to her face (and the coach's too).