Internal Dropship and line warehouse LOV's

Hi

I have posed this question earlier but I could not receive any satisfactory response and hence I am reposting it. I am on R12(12.1.3) vision instance and here is what I am trying to do.

Per my understanding in an internal drop ship, the seller will ship the goods directly to the customer(however it is a different OU,say OU2) rather than the OU that booked the order,say OU1. So if that is the case, at the order line level the warehouse LOV should bring up all the inventory orgs corresponding to other operating units as well,so I can pick an org corresponding to any different OU. However I am only seeing four inventory orgs which are corresponding to the current operating unit. If that is the case how can I create an internal drop ship order.