I'm working on doing that programmically, from Sybil, with a Linux broadcasting bot that runs with my npub.

I don't know if it needs to be within a relay, but it's a nice sort of plug-in or utility.

Like, if I write something directly to my laptop relay (ws://localhost), I want it to broadcast to TheForest and TheCitadel, but nowhere else.

If I write something to sovbit.host, I want it to broadcast to a whole list of relays and auto-repost 6 hours later (cuz of time zones).

And I want to regularly pull everything from my follow list from that long relays list (excluding AUTH relays, to protect people's privacy) and broadcast it (and any embedded notes) to my localhost relay, theforest, and thecitadel.

Then I could just write to the one or the other, like having public or private channels in a logger.