That makes much better sense to me, thanks. I still don't see this as being much different than using RW on multiple devices. You still must sync your changes, and I believe there are safeguards in place to keep you from syncing a ream from one device that has been changed on another (although I could be mistaken, and if there aren't there should be).
If you can't share a login, and you don't think the sharability of realms will be enough to successfully collaborate, then I agree that your idea should be possible.
