Automatic Location Assignment Tables

We want to use the drop ship PO system within NetSuite.  But we have multiple vendors for the same product. So far, from what I have read and from our account rep, there appears to be no way to “allocate” sales order line items to a particular vendor based on the destination of the shipment as  you can do with Automatic Location Assignment for non-drop-ship items.

If I do not mark the item as a drop-ship item, I believe that I can pick up the item in a workflow and mark it as drop ship to a specific vendor, but I need to be able to pick the appropriate vendor.

Does anyone know of a method to do something like this or is it possible to use whatever system the Automatic Location Assignment uses to pick a “location” since I can tie a vendor to a location in a  custom record?

thanks