Send Separate Remittance Advice RTF Customization

Summary:

We have customized RTF template for sending remittance information to the Supplier. We are pulling PO number from the invoice line level along with payment information which is generating from the payment batch. Client asked us if the invoice is having multiple PO numbers on the invoice, then it displays as 'Multiple' otherwise it display as POnumber which is matched to that line. If the Invoice is matched to invoice and if we have other NON-PO lines, it showing as 'Multiple' Can someone please let us know how to take the not null PONumber field in BI PUblisher.

Note: XMLS tags gererated by payment batch we do not have the option to modify the query. We have to write the logic in the RTF only.