Billie Farrow likely knows all of my Hogsmeade folks at least in passing. She specifically loathes Leo Lupin and snubs the shit out of him.

Zachariah Binns probably has the most connections because he owns a bookshop. I headcanon/mention all the time that he has found Billie books she enjoys reading in order to encourage her to catch up with kids her age. He's also likely helped Archer Belby, Thomas Montgomery, and Edison Moony with their research on numerous occasions.

As far as Hogwarts folks, Thomas thinks Archer is a baby and doesn't bother with him. Thomas is also probably on polite terms with Ned, but they're not friends.