M.R.
Aww poor girl. Yeah, you are right. Just have her use it where she gets acne. I agree with the prior poster too about the exfoliation. She might be getting it also because she can't reach her back to wash it very well, so make sure she is finding a way to wash her back every shower (that's where the brush might come in handy). Also, have her take a shower after she sweats (like if she does sports).