It isn't feasible to link a purchase order to a sales order in any setup except for the direct delivery setup. The linkage appears on the "Item Reference" and "Reference Number" tabs found in the sales order lines and this linkage is done automatically by the system once a sales order is created. This forces the clients to always choose the direct delivery set up in order to have the leverage to link a purchase order to a sales order. Moreover, if the customer then tries to remove an already linked purchase order and choose a different one, the system will not allow this action. In case of high sales demands, this process can be very labor intensive as the customer is then tied to cancel the sales orders all together and re-link them to new purchase orders.