As1MDNURL in TN profile setup

Can someone clear up what the AS1MDNurl is for? My understanding is that it is the URL or (e-mail address) that is to accept inbound MDNs. So if Partner 1 is trading with Partner 2, Partner 1’s profile would have in the field-- since and MDNs that are in TN for partner 1 would be delivered to (… and Partner 2’s profile would have their own e-mail address in the field. (… the way we have it setup currently is switched… they have each other’s e-mail address in there for AS1MDNURL… but doesn’t this limit it to a 1 to 1 integration… What if Partner 2 wants to deal with Partner 3? Can someone help me?