One other thought after the long novel I just wrote above: most of the negative comments I got were along the lines of "A grade skip/early entrance may not be a big deal NOW, but when they hit puberty/get to middle school/ get ready to go to college at just 16 . . . ." That makes it almost impossible to argue. And it implies that the other party clearly knows more than you do. Stand firm. I always just say that we're caring parents who are willing to cross those bridges when we come to them. Just a heads-up, though, so you can get prepared with your responses.

She thought she could, so she did.