Allowing change of Bundle promotions at Order level

Hi Gurus,

I have a request from the customer where-in they would like to have a functionality similar to the 'Upgrade' of Bundle promotions at Order level. Currently we have Upgrade & Downgrade of Bundle Promotions implemented at the Asset level where-in on Modify we present them with an option to upgrade or downgrade a bundle and the list of such is presented to the users. On selection of it by the user, delta computation is done and the Order is generated with appropriate action code i.e. Delete if the product exists on the asset but not on the Bundle Promotion selected