A drill that helped my daughter was to stand on only her pivot foot. Hold her back foot up in the air behind her. Get balanced and do her pre-motion and rock both hands forward to 3:00 then back. Repeat and then execute a full pitch.
You might want to try the walk though drill, have pitcher start a few steps behind the plate and walk up and pitch.
Not sure what people think about the pitcher starting in sprinter stance and exploding off the mound but this might help stopping them turning their foot too.
mounty are you saying she is not turning her pivot foot? Like she is staying over the toe and staying closed so that is what is causing her to bump her hip?