I almost overlooked the last sentence, but this is something that the streams repository supports and I should probably expand on that.
The premise is simple. My conversation is a container that I own and I choose the audience for everything in the container. You can make comments and you own the comments, but I own the container and have the ultimate authority of what gets put in it and who those comments get delivered to. It's not only my container, but it's also my audience.
We have heated debates and disagreements with the microblog projects about this concept all the time. But this has been a part of the fediverse since 2010 and we aren't going away.