What do I mean by that exactly? Allow a community owner to combine their community on their instance with communities on other instances.

gaming@lemmy.A wants all content from gaming@lemmy.B to show up in their community. The content wouldn’t be duplicated, rather show the content from gaming@lemmy.B to any gaming@lemmy.A community members. Anything posted to gaming@lemmy.A would appear in the community for gaming@lemmy.B. Anything posted to gaming@lemmy.B would only appear on gaming@lemmy.B.

gaming@lemmy.B decides they want to federate with gaming@lemmy.C. They would show content from B and C. gaming@Lemmy.A would show content from all three.

gaming@lemmy.B decides they also want to federate with gaming@lemmy.A. Now, B and A both show the same content from all three instances. gaming@lemmy.C only shows content from its instance.

At any point if a community on an instance become problematic for any reason those instances can be blocked by community owners.

There should also be a way to allow community members to block content from federated servers, even if that federation is done at the community level.