If you download an event registration for a participant who already is on the event record as invited (previously added by a user), any attributes tied to the registration should transfer over and not be lost.

It's important to track who have been invited to an event, so it would be helpful that when they do register that we can process over all attributes/information provided vs losing it. It should be an update to whose invited, not a wash of information since they are already on the event record.