Wow! Her form looks so much like my dd just 6-8 months ago when she pitched about 50-51 mph. She's a Dec 96 and physically very comparable. She too had an issue with her body being ahead of her arm. Also, like your dd, she kept her arm very straight on her backswing. With her new PC, she's relaxed her arm on her backswing which allowed her to get it through faster on the downswing and also got more whip action. Timing is getting better all the time. She's up to 55 on her FB and is getting a little faster each week.
She looks pretty good IMO. I'm looking forward to reading what the guru's have to say. Please post more pics/video.
Without you posting a video it is very hard to see things like timing and body position through the delivery. If you are talking about maximizing her performance you should be talking about what pitches she throws. With that being said, I too agree with Sluggers continually intuitive assessments that he believes the body is ahead of the arm.