If you are going to make any change(HE to IR) forget full motion for now and work from the K position. It will make life more simpler. Have her get in the K position with stride foot at 45, drive foot on her toe and ball palm up. By doing this you are already eliminating 3 things to worry about. Keep practicing by throwing in this position watching for posture. From this position make sure to remind her to lead with her elbow and pinkie and drag her toe going knee to knee. After doing this proficiently, you then get in front of the rubber and have her start with ball in glove around shoulder height. You then step and throw making sure to get foot at 45, palm up and toe dragging.After that you can add a little leap and drag then to full motion. Keep progressing until mechanics break down. This is what i do with my pitchers.