Odds are if she is using a baseball bat the bpf is 1.15. In theory, a Fastpitch bat at 1.20 will produce better results (if everything else equal). If you're just playing independent tournaments its doubtful anyone will care if she's using a bat that isn't as productive as possible. In sanctioned tournaments the respective stamps are required. If you buy a used bat make sure it has the USSSA "thumbprint" stamp. There are tons of options for fastpitch bats (and bat /sizes/weights/prices) so you probably won't have much problem finding a drop she likes. I would suggest contacting CoreSoftball20 on this site. He is great about helping people to find the right bat (and the right price).