When receiving and before validating the products, we want a pre-process to do first.

• Check documents like Packing List if it is match with the Purchase Order. 
• Check Product's quantity and description if it is match with two documents.

So, if there is a discrepancy with the either of those 2. The product's will be put in Holding Area or else, return to vendor.

Is it possible for that? Because we tried to enable the 2-step process (input+stock), but when we clicked the validate button in Inventory/Receipts, the Odoo automatically count it as On-Hand.