Helloooo! So! We've discussed things, but I think I have some others connections!
For Indiana, Josie is in the same grade as him in school! So I feel like they would know each other and have for a pretty long time. I also feel like they'd get along! Other than that, I have Calla, who is teaching at the high school so he'd might have had her for an English teacher at some point
For Ethan, they'd have been a couple years apart, but he and Nick would have had overlapping years in school and they were both into theatre, so they could have become friends through that! Nick did go into theatre after graduating, but he's been back in Dunhaven for a while and doing local community theatre stuff.
For Albert, the Hylands are likewise a very old money family the settled in Dunhaven so I feel like that could have made them and the Parkers family friends? So he could know Rowena through the family that way. Otherwise, I also have Calla as Toma's sister; her relationship with Toma is complicated, but she'd be nice and friendly if they saw each other, like she always is. I also have Alex, who was a year ahead of him at Aurelius, so there could be some friendship there, too.
And then Zee! Other than Alex, none of them will know her yet, of course. :3 But! Calla is bff with Alex's fiancee, so there's possible friendship there. And if she makes it to school, I have Rowena that could meet her there for friendlies.