Hello and welcome! I'm Jo, and 3/4ths of my characters don't have completed bios because I fail at time management but we can discuss them anyway.
This is Keziah, who's a fellow 7th Year Hufflepuff so they obviously know one another. Kiz is in the Sporty social circle, which means she spends time hanging around the Quidditch Pitch, where Miles will occasionally be because that's where Quidditch players and Troublemakers hang out too. Her cousin/twin (that's totally a thing that makes sense) Basil is in the Troublemaker social circle as well, which means she's probably had even more cause to run across him. I can't imagine her liking Miles at all, but she might be civil because he can find things and Kiz sells things, and occasionally she gets requests for things she doesn't have yet so she needs to find out who DOES have them so she can go buy them and resell at an unreasonable mark-up.
I've also got Cameron Ayers, a 5th Year Ravenclaw who's actually pretty similar to Miles in many non-personality-related ways. They're both muggle-borns, both Quidditch players (well, Cam will be soon enough), both Psychics and both members of Book Club. If they can't find something to do, we're just not trying.
My last two girls are something of a conundrum. Charlotte Quong is a 6th Year Slytherin and Nora McLaggen is a 4th Year Gryffindor. They haven't got anything in common with Miles BUT! Charlotte's in Choir and Nora's in Cooking with Charms, which both take place in the disused dungeon that Troublemakers occasionally hang out in. Plus, we've got journals to help us facilitate things, so I guess we'll see how it goes.