Swap shipment between 2 different carriers

Hi,

I try to figure how I can setup OTM to respond to this scenario.

I have a multi-stop shipment and I want to swap this shipment between 2 carriers.

From source location A to destination location X,Y,Z.

Start the shipment with Carrier1 and in the middle, I want to swap with Carrier2 and this carrier do the deliveries.

Here is what I try;

1- Multi-leg itinerary, but I can't set as a multi-stop, the bulk plan created 6 shipments instead of 2.

2- I can't use the swap shipment's action, it's not a fleet shipment.

3- Using the pool can plan the second leg differently as the first leg. I need to keep the shipment on leg 2 as is built on leg 1.