WMS directed picking based on UOM

A client has a large warehouse where the same item is held in different location depending on the UOM, ie PALLETs at the back, CASES in the middle and EACHs upfront. Sales UOMs are appropriate. Base qty is EACH. Decimals are not allowed. Pick on Location order or location priority does not work. If a customer orders a PALLET then the correct location must be found. If the customer orders a PALLET and a CASE then pick should be from two locations. With Wave picking there should be two pick lists. Is there any way to achieve this or a WMS add-on that will do it?