Inventory and Scrap UOMs

We have one material, paper, that we use to make our paper bags. We inventory in 'Cases' a part specific unit. All of our scrap we calculate is based in LBs of paper. Is there any way we can set it up that the scrap is recorded in the LBs quantity and not cases as it would be unreasonable for our operators to count every bad bag that comes off of the machine and all of the scrap created while trying to set the machines up can't even be counted as bags because they are not bags yet. We are looking to be able to do this at the MES end activity