Harry Potter plot idea with Vampire

Witch turned Vampire, who used to hide away from wizard society, becomes contracted as a builder for Hogwarts. History shows that she's constantly been changing careers and locations to be less sus since before the romans arrived. So when commissioned by Minny, her past as a seamstress and her old babysitter can't be hidden. However, one of Harry and Ron's first assignments is to bring in unregistered magical creatures attached to the school. There is a scuffle and she is only allowed to remain on recomendation by Minny. On the condition she also remain a grounds keeper, so she remains doing both (for diff smaller schools, a general worker) and a grounds keeper for hogwarts.