Whenever you make updates to the timeline, everyone on the shared timeline will receive an update email, letting them know what changed in the their timeline. You do not need to share the timeline again after making changes.
The email is sent 30 minutes after the last update to the timeline. If multiple edits have been made, Folio will roll all updates into one email:
If you add reminders to events, that will also result in emails being sent to anyone the timeline is shared with, on your specified reminder date.