Hi there, Lynn! If you're still searching for connections, I have a character who could be a good fit for Oz, Ezra, and Ford. His name is
Beaumont Chamberlin; he, too, works for the Ministry, though as an Auror.
I am open to exploring the dynamics of his possible relationship (platonic and/or professional, of course) with them, whether it is positive or negative, since I'm sure he may have encountered one or all of them at some point during his time in the Ministry thus far. It's also possible that Beaumont may have known Ezra before working at the Ministry as some sort of acquaintance—if not friends or classmates—as they attended and graduated from Hogwarts at around the same time, though the only difference is their House, as Beaumont was a Ravenclaw. They may have gone through the same Auror training program, too, upon graduating!
Another character that could be a good fit for Ford personally is my main chickadee,
Cordie Howlett; she had gone by her maiden name,
Cordie Middlemiss, before marrying her now-husband, Salvatore, and had stepped down from her position as Art Instructor. She may have known Ford during their time at Hogwarts—not to mention that she, too, was a Hufflepuff. How their relationship may have played out during and after their school years is up to you; I'm open to exploring that dynamic, too.
I look forward to seeing how these potential connections would blossom, though no pressure if you aren't interested; figured I'd throw a couple of characters your way!