Payment of zero dollar invoices only through PPR

Summary

User wants to make the payments through PPR which results into zero dollar amount.

Content

I want to have a payment template that should select only the invoices which have the amount of zero dollars or results into zero dollar (due to the nullification of credit memo and standard invoice) so that I submit the payment request and can mark those invoices as paid.

I have tried the following options but not yet successful:

1. Document Validation at Format Level (Document Amount to be paid is less than or equal to 0)
2. Payment Validation at Format level (Payment Amount to be paid is less than or equal to 0)