And there's that incredible weirdness in CoS, where it doesn't ever seem as though the Grangers are even notified that she's been petrified/don't seem to notice they haven't heard from her for a *quarter* of the school year. I know some of that can be explained by the "Harry filter", but then how does one reconcile that against the fact that Montague's parents are explicitly mentioned as showing up at the school and being really unhappy about his condition in OotP? I suppose it's the whole "Muggles can't see Hogwarts" thing coming into play, but still. There's no evidence the Grangers even notice they've not heard from her in months.