In medicine we lump UC and Crohn's because they are both inflammatory bowel diseases. I think it's entirely reasonable if you do the same (at least / especially initially).
I've been diagnosed with UC 10 years ago, only recently doctors changed their diagnosis to Crohn's disease (btw it's called Leśniewski-Crohn disease here). Apparently it's hard to distinguish, and I think it's good to keep them together.