Updating shipment weight, volume at header level

Hello Team,

We deal with lot of weight based shipments typically LTL and also AIR shipments. OTM plans the shipment based on weight, volume entered on order and later service providers invoice us for a different weight that was actually pickedup.

So to reduce the fall-outs on invoicing, we decided to use the weights provided by carrier during pickups/deliveries through EDI or carrier login. The question I have is, carriers provide weight, volume updates at shipment level (total shipment weight) and not at ship unit or ship unit line level. My understanding is OTM cannot re-rate the shipments just by the total weight, we need to update at ship unit /ship unit line level. Is that right? I believe its a typical issue for all clients where carriers send weight at shipment level and you wish to use that weight for