Maybe dejongj can throw some light on this re whether owners can keep their original tyres as he seems to be in regular contact with his dealer?
Unfortunately it comes down to the dealer interpretation. I'm not accepting a swap, I don't want to have reduced performance in my car by moving to all season tyres. But my situation is slightly different as there are no tyres available. So I only accept 20" wheels and tyres as an addition to the 21" wheels I've got. And I would suggest you also discuss storage with your dealer