So, of mine, the most obvious connection is Marlene. Younger sister and future-fellow-Firefly-dreamer! There's ten years between them, so I don't know how close they'd have really been growing up, especially with him being off in boarding school and then into the military. She'd have been in boarding school herself when he came home to Dunhaven permanently, but there probably would have been more opportunities for family things at that point, especially once Kylie came around. Marlene absolutely adores being an aunt. She probably couldn't do much in the way of babysitting until she finished at Athena in 2016, but since then she'd be all about it!
Lorelei is engaged to Foster, and has been coming to Wentworth family gatherings I'd say probably since Thanksgiving-ish of 2018? Maybe slightly earlier, Terri can chime in there. But she is v v v v excited to be a Wentworth (in 41 days but who's counting). And she also adores Kylie and gives her a free scoop of ice cream any time she comes into the Dreamery.
Dahlia is a fellow Air Force veteran, though I doubt they'd have really had much overlap, other than the fact that Papa Wentworth was one of the people who helped guide her toward that career. Much respect.
A few others are Dunhaven natives and/or in public service jobs, but no direct connections that I can think of.