I'm not quite sure what you're describing here, the summary is that I use the inbox model to send shared keys to members. Those invites have relay hints to help them find the group. Everything is wrapped using the nip 59 draft. You can read the spec here: https://github.com/nostr-protocol/nips/pull/875

Thanks for liking coracle! The new release removes several old features which I hope to revisit later.