Transfer Order Shipment costs

We do several jobs that have a subordinate job in a different site. We are good with the transfer and receipt to the parent job. My question is that when we ship the child job from site A, there is shipment cost that we would like to roll up into the parent job in site B.
I’ve wondered what happens if we put that shipment cost in one of the manifest cost fields on the TFO Shipment. Unfortunately, I think it does nothing.