Transport Legs and route stages

Hello experts!

I'll try to explain the task using an example....

- we've a sales order with tow items, the fist one from PLANT 1 (delivery 1)and the second one from PLANT 2 (delivery 2).

- we've a stock transfer order, with supplier the PLANT 1 and destination PLANT 2 (delivery 3).

And we have to planificate the shipment in both plant BUT the shipment to the customer is from the PLANT 2:

Transport 1 (from plant 1):

- delivery 3

- Delivery 1 (from plant 1 to plant 2)

Transport 2: (from plant 2):

- Delivery 2

- Delivery 1 (second leg??

Question: I don't khow how to configurate the route from plant 1 to plant 2 for the customer: route with stages? or shipment types with different leg indicator???

Do you know a similar situation???

Thanks in advance.