Nate should know Chuck. So should Ollie soon, if not already. And Claudia is friends with Hayden and Robbie both, so he might know her, too. He's also about the same age as both Dari and Charlie's so he might have known them from LPA and he might remember my current LPAers. Ummm Teegan is Robbie's BFF, so he'd definitely know her, I think and he might remember Dora. She was only a Sophomore last year, but she's pretty popular, so there's a chance they met at some point.
Josh? Sounds a lot like Teegan, actually. There's a pretty big age difference, but if we could find a way for them to know one another, I think they'd get along really well. He also would have grown up with Henry and he's pretty close in age to Lyla, too. Aaaaand, he might know some of my people in Seattle. Maybe something with he and Jules, since she's all into music?
I'm open to any other ideas you might have, but that's what comes right to mind for me.