Add a filter to the “Inventory Replenishment” form to so that it can look at inventory on hand, the min/max/reorder point, sales activity, etc. on a per warehouse basis. This will help generate inventory replenishment purchase orders by warehouse in a more automated fashion.
Add a spot on the PO to assign it to a specific warehouse.
Each warehouse has its own unique PO numbering system (i.e. 21-0001-“WH Name”
Carry this information all the way through the item receipt and subsequently the bill.