Store local/personal data for calendar items in group calendars created by others
There are a number of aspects about a calendar item that are personal/local. The obvious standout is reminders. Even if the organiser of an event sets reminders, they may not be suitable for all participants and I might have a different idea of what a set of useful reminder intervals is for an event.
I can try to edit such an item and add my own reminders, but I am quite quickly told that I am not the organiser and therefore cannot edit.
In this case, it would be nice if Evolution allowed me to edit the event, keeping my edits locally, such as reminders that I would prefer in addition to or instead of the organiser's reminders.
There are other fields ripe for locally stored data. Most in fact, probably other than the core data, such as date/time/attendees, etc. But Summary, Location, Web page, Description, Attachments all seem ripe for allowing local edits.
There comes the obvious question about what happens if the pre-existing calendar item, for which local edits have been stored, have some fields that contain local edits, have some of their items modified. I'd suggest that calendar items, (IME) are rarely amended like that and so maybe just reverting the fields in the calendar item back to what's in the calendar and popping up a window with the list of local edits, for the user to re-apply as they desire is sufficient.