The part of the code which requires the separation has nothing to do with function, previous codes we were able to "cross-vent", someone on some committee thinks it's safer I guess. I think it popped up in the 2001 code. This is the wording, part of Chapter 9, section 910: Only the fixtures within the bathroom groups shall connect to the wet-vented horizontal branch drain. That's from the Florida Plumbing code which is almost identical to IPC.
I'm having trouble acutally seeing the arrangement, specifically the angles some of your fixtures are on, can you post a plan view(where are the walls located)? I will give it a shot until then. It looks like everything is fine but you can combine the sanitary at the first floor, it just has to be downstream of a bathroom wet vent (the sink/shower part of the system).