So FJ takes place before Gringotts, and if you flash forward some more to a MM ride, that gives you two options I think....
- You could probably get Ron. He and Harry are both working at the Ministry a few years after DH2. You could explain it away as Ron trying to keep things under control himself and not wanting to run to Harry for help with whatever is going on. It's a lot easier to make him look like a young adult than a high schooler again.
- If you really wanna get wild....Hermione is Minister of Magic 19 years later. There's all that controversy regarding the casting in Cursed Child, but she did get nominated for a Tony. You could also go after the Potter from the play.
I know either one of these breaks the trend of staying totally true to the movies...but it could broaden the horizons a bit. Unlikely, for sure, but fun to think about.
*Note: I haven't read much on Cursed Child. I'm seeing it this fall and trying to stay clean.