Over receipt in receipt routing

Hi,

We are using receipt routing for out imports. the receipt routing steps are Sea - Customs - Stock. In some cases, the supplier sends us more or less quantity (in tons or cubic meters) than what was originally ordered in the PO. The only time we know for sure what the actual quantity in the shipment is when the goods reach our premises (last step in receipt routing - move to Stock). Hence we would like to be able to adjust the quantities accordingly. Typically the differences are in the range of +-5%. If the actual quantity received is less