I need a good Harry Potter admin name?

[Melanie]

You could go with Madam Rosmerta, who worked at The Three Broomsticks.
Other suggestions:
Rose the Weasley
Rosethegryffindor (or whichever house you are in. I said Gryffindor because its Ron & Hermione's house, but you could use any of the houses)

I'm sorry, I thought I could think of better ones than this when I started answering the question. You could use something to do with Scorpius, as many seem to think they'd get together when older?

Sorry I couldn't be more help, if I think of more, I'll try to edit the answer (I don't know if that's possible)

What page is it? I want to like it, I could always use more HP fan pages.