I'm putting together a game involving a time loop (which means the timeline/calendar will be _amazing_), but I'd love to be able to track events across multiple calendars.
For example, I want to have a timeline that is "NPC X's Schedule", that shows what a given NPC is doing on a given day (and thus where they are), and another that is "Events in District 3" that shows things that are happening in a given area on a given day. I could probably think of a couple more timelines that would make managing the story easier, too.
At the moment I'd have to duplicate the event on multiple timelines, whereas if I could tie an events to multiple calendars when I create it / edit it, that would be fabulous.
In addition (and I'm almost tempted to suggest this as another feature on it's own), being able to change the date of an event that is synced to document would be cool. I appreciate multiple events might tag back to a document could make this difficult, but being able to edit the date of an event from the document would be great for a smooth world building flow.