event tickets - user self service - user can add or subtract one or more tickets from his event registration
For almost all my complex events, my users need help changing the number or type of ticket they have. This should be so easy they should be able to this one their own without admin support.
This includes adding or subtracting ticket(s), even all tickets thus resulting in a full cancellation.
This may or not be possible within the Profile. HOWEVER, this should be doable within the event experience, eg clicking on the event and seeing a button "modify registration".
The number of additional tickets would be governed by the ticket purchase parameters.
I also agree that a modify registration macro should be available to include in the event invitation and reminder emails.