If she is young she might not throw or spin it hard enough to break. Ok, to play with it but not going to move.
Some good college pitchers only use a fastball and change up.
Change up needs to be 2nd pitch, good changeup is deadly.
Her family wants her to throw her curve . ��
I wouldn't recommend a flip change simply because the back spin. A "splash the cup of water" approach will be more deceptive and the spin will be forward.
I have found the exact opposite just watching from the sidelines. The "water splash" or "handshake" change requires the pitcher to extend their open hand and fingers towards the batter, and I've never seen a girl throw it without slowing their arm speed. Not to mention that it hardly spins at all -- it usually looks like a knuckleball. Maybe there are some pitchers who have really excelled at this, but it's been obvious every time I see it deployed in 12U.
The flip, on the other hand, requires a full-force delivery just to reach the plate. And the spin dynamics work well along age lines: at the 12U level, hitters are not able to distinguish between backspin and forward spin. By the time they get sophisticated enough to recognize the spin, pitchers can throw a rise which looks similar to the spin on a flip.
Just the defensive reaction of a parent whose DD throws a filthy flip