Let's assume I have a user, John, who has already shared his calendar to a group of his-coworkers. The company then hires new employee Jane. Jane would like to see John's calendar in her Zimbra web UI. Does John have to "re-share" his calendar just to Jane, or can Jane (or an admin from the CLI) somehow hook into John's calendar from Jane's account so she can see it?

It's my understanding that even if a user doesn't accept a share, as long as it has been shared in the past that share is still available.