How to bring shipping into Requisition from Punchout?

Summary:

We need to bring shipping costs from the marketplace punchout cart to the requisition. I know this is a gap and an idea exists but there must be a way of cutomizing to provide a solution. That is what I am looking for.

Content (please ensure you mask any confidential information):

We are using a marketplace punchout site which hosts multiple customers. So the punchout cart will have lines from several different suppliers and will include different shipping charges for these suppliers. How can we capture the shipping costs on the req and convert these to freight costs on a line ? (DFF, API etc) Has anyone done this? There must be way surely as this is a common requirement? How have we met this requirement at other sites?