SD/OD branch plant setup required

In the past, we have had SD/ODs set up where my company handled the transportation.  In this case, each third party supplier was set up with their own branch so that the transportation could be arranged.  The The sales order was ship confirmed manually and received after that.    Inventory was never maintained at this branch, and the D line type used.

We now have a requirement for 2 now suppliers to be set up for direct ship, but they will arrange transportation themselves.  This seems like a more traditional SD/OD configuration.  Based on my review of the available documentation, it appears that manual ship confirm is not necessary and receipt would occur when the material arrives at the customer.  It is not clear if a branch plant is needed for each supplier.   If not, what considerations in choosing branch to be used on the SD and how does the correct supplier number (in our case supplier A or