After working with bunches of girls over the last 6 years this kind of inaccuracy means her mechanics are not even close to correct. Whether it is overhand throwing or underhand throwing if the kid is athletic and can get the basic understanding of how to throw (over or under) they ought to be around the target. "Another pitching coach" may not be the answer. They may simply reinforce the nasty habits. If you personally are interested in having her pitch you need to be able to understand where here mechanics are basically flawed and see if she can get on the right track with at least some basic drills under your watchful eye. If not...just let it go and maybe she'll luck out and run into someone who can and wants to help her and her family see the light.