During receiving P4312, add freight charges

Seeking ideas how this scenario is handled.

For some of the deliveries of contracted suppliers, they will include the delivery order (for items order by PO) and a separate invoice charge for the freight/packing charges. These miscellaneous charges vary by order basis, hence at the point of PO entry we do not know the charges yet. It will only be presented during delivery (there is an agreed basis for the charges).

Warehouse would like to capture these freight/packing charges at the point of PO receipt. Similar with the confirm shipment, we can add a freight line to the sales order.