There should be no concern for an IP when keeping the ball hand in the glove as long as possible. Under ASA, you have 1 to 10 secs to start the delivery of the pitch after you have taken the sign from the catcher and bring the hands together. Once you start the backswing, you can keep the ball hand in the glove AND keep them together during the forward motion as you push off of the pitching plate until they naturally separate when the glove is pointed to the catcher (around 9 o'clock). Right now, your DD is showing the ball early on the backswing and as the pitching hand comes forward. Why not hide the ball and grip for as long as possible which gives the batter less time to pick up the pitch.
Some argue that you lose a couple of mph on the pitch if you keep the ball hand and glove together on the forward push-off? I'm not completely convinced of that. Look at the best male fastpitch pitchers, almost all of them "hide the ball" and they throw very hard.
Regarding your other point about foot placement on the pitching plate. I think you have it reversed in your description. The pivot foot toe should be on the front portion of the rubber, and the stride foot is placed on the back portion of the rubber. I don't have the rulebook in front of me, but I believe the foot needs to be "on" the plate, not just touching the "back" of the plate.
My previous comment about your DD was that she was moving her right foot (pivot) forward off of the plate, and then pushing off a second time during the leap and might be called for a "crow hop".
You last comment, both of her feet will be on the pitching plate as the hand goes back during the backswing, when she pushes off to go forward, that is the time her stride foot will leave the plate during the leap and drag, she will drag the pivot foot along the ground. Your PC should not be concerned.
Lastly, the pitching carpet she is using seems to easily buckle when she pitches and causes her to lose balance, might even be dangerous. I would either tack it better to the floor or get rid of it completely. It difficult enough to pitch without introducing an unstable foundation to pitch from.
