hmm, i'm still having a hard time understanding what the issue is. couldn't the app just have "@instance" at the top of the post? and if it's blocked by the instance you're registered on, isn't that just intended behaviour and a consequence of choosing the one you did to register? i'd want those posts to be hidden from me if it's from say a problematic instance that mine blocked.

In my head, the way it'd work is when you go to subscribe to a community, it prompts you for which of your multireddits you'd like to add it to (which you can create and name right there), and those multireddits are what display on your sidebar