Bah. At first, I thought this was going to be a situation where the author just took ideas from another. Legally and ethically, that sort of thing is okay. Ideas get used and reused a hundred times over.
But actually taking physical text and swapping words out here and there? No. If you're going to take an idea, maybe even an entire scene, at least rewrite it. Even if this girl's book is great, the notion that she ripped off another author's words smacks of supreme laziness.