The thought is that the Calendar npub will be the one that creates all of thier events. Then if you want to allow multiple event admins to edit, you can just set up multi-access to the calendar pubkey through a bunker. 

 That's very similar to what I did for private groups
https://github.com/nostr-protocol/nips/pull/875 

 Group Chats are the best way to bootstrap all of this indeed.