For Thistle Potts :
I can either have @"Percival Adlard Jr." be hurled at her now or I could almost see him being a Ghost of Hurls past. He really wasn't looking for anything until now due to a heartbreak in his early 20s, but I could see him having attempted to rebound due to pressure from his friends. As for classmates Rufus Bixby may have known her. He is a year or two older and was in Gryffindor, but I'm pretty sure he would have talked to a doorknob if given the chance. Kenton Yaxley is also around her age and was in Slytherin. He's not the nicest guy but went into Plant healing so I could see him having ended up running into her at school in the greenhouses or in the shop. Up to you if you'd want me to hurl him or have him just be a passing person she knows.

For Temerita Reid :
I have @"Nimiane Bellchant" in Irvingly. She keeps to herself a bit as a squib, but she writes lots of books (not that anyone knows that) and I could see her having a conversation about just how do wands work at some point. Up to you if that comes about now or if that has been in the past and now they are friends and Nimiane asks her all kinds of magic questions.

For Edmund Grimm :
I believe he is only two years ahead of @"Percival Adlard Jr." and in the same house so I'm sure they would have at least known each other. I could see them as perhaps getting along as work friends? I can also hurl @"Lucille Flint" or @"Caroline Delaney" at Ed if you are interested in hurls. Unless he wants spinster and magicless @"Nimiane Bellchant" thrown at him, but she's done looking for romance.

For Killian Macmillan:
I have UCPB Kenton Yaxley who works for St. Mungos. I am toying with him being up at Hogsmeade hospital to help with the fog even though he'd much rather be left to his own devices in London. So they could run into each other there. Or perhaps before then. Up to you. Also Kent is a member of Black's so they've likely run into each other at the club.