If we have multiple items that we purchase at multiple vendors. That means that one specific item can be purchased at two or more vendors. Based on the vendor selection, the unit conversion may differ. For example, item A is purchased at vendor 1 and vendor 2. At vendor 1, 10 pcs in 1 box and 10 boxes on 1 pallet (=100 pcs). At vendor 2, 20 pcs in 1 box and 6 boxes on 1 pallet (120 pcs). If 600 pcs of item A are being purchased, than vendor 1 sends 6 pallets, as vendor 2 sends 5 pallets. That means at purchase order receiving, for vendor 1 6 license plates need to be printed, as for vendor 2 5 license plates need to be printed. 

Based on single intra-class conversion and multiple intra-class conversion it is not possible to automatically generate the unit conversion based on the vendor selection on the purchase order. We want to be able to change the unit for each and every vendor.