With Ply I'd test the crew side first. if material leaves a truck and nobody records it on the visit, the inventory count will drift pretty fast and soon nobody trusts it. If a supplier delivers short or sends the wrong quantity and nobody catches it on arrival the stock count is wrong from day one. We built checks that compare supplier confirmations with the purchase order for quantity price and delivery timing, then compare the invoice with what was actually received. Send me one of your jobs and I can show you how those checks would handle the purchasing side.