Partition based unsubscribe data

So we've recently added a couple of new workspaces and lead partitions to handle a new brand we've added. We have Brand A, Brand B, and Combo. Our unsub/subMGMT page has snippets and segments to show each lead the proper form to manage their subscriptions. We've added new data values for Brand A unsub and Brand B unsub so any combo users can opt out of one brand while still receiving emails for the other brand. That brings me to my question, Brand A is a very established workspace in Marketo with thousands of emails. Is there a way to more systematically tell Brand A partition to not send emails to leads with a particular data value, for example Partition A don't send emails to anyone with unsubBrandA of true? I'd love to be able to avoid editing the smart lists/campaigns of all of our legacy emails for Brand A. One idea I had was to have a listening campaign where a lead in Combo unsubs from Brand B, then move them to the Brand A partition. But that seemed to get more complicated as leads opted in and out of different brand emails. Hope that question makes sense. Any help would be appreciated!

Thanks!