We have many zero dollar POs that we can't close because there is no invoice to match

We have business situations where we must issue POs to get product components from a customer (to be delivered back to the customer as finished goods.  In these cases there is no dollar amount to the POs.  This creates a problem where there will not be an invoice to match so we cannot close the POs.

Where possible, we are using the "Payment on Receipt Autoinvoice" by flagging certain suppliers so that the invoices are automatically created.  However, there are a large number (thousands perhaps) that this was not set for and we need a way to either get them to close or auto-create the invoices to match so they can close.