Acumatica allows creating or linking to a PO from a sales order. When a sales order line becomes marked for PO, its plan type changes to 66, “Sales Order to Purchase”. The total quantity of the line is added to the PO, and it is not possible to mark the line for PO if there were partial shipments done (backorder).
Also, when goods are received, the sales order line is re-planned automatically to “SO Booked”. At this point, the goods become floating and can be stolen & shipped by another sales order. Goods should be allocated at this point so that the shipment process cannot assign them to other orders.