Originally Posted by GigoloShawn

The easiest way I can think of doing this would be to abuse the "Approval Post", and the "Rebill Post" urls set for each site under Site Admin -> Site -> Edit Site. Read what's sent to it on $_REQUEST, and if possible, match up with the data in the member's table. Then, you can have it fire off an email to your shipping department each time it's rebilled, and they can handle each transaction as an initial sale, as most simple gateways do.

The memberidx (subscription id), and all information related should be posted in the $_REQUEST, but it can, and does vary between NATS revisions, so check to see what you have available, and fill the rest in with a WHERE SQL clause.