I have no idea, i imagine it would be like a multireddit. The initial creator curates it, but the mods of the communities admin. Copies can be made if you don’t like the original collection, or its been abandoned?

I would hope a collection would have a bit more deduping/crossposted logic?

But i could see even having it so you can post to a collection- but before posting, it asks you which community fits best (ranks similar names by subscribers) this way you post to the most popular one. This should naturally make the user base gravitate to one or another.