GST REFUND ( SAME FIRC NO FOR DIFFERENT INVOICES)

Dear Professionals,

We are applying for GST Refund. we need fill the Invoice details against which we need to provide the FIRC details.we have received 1 payment for 5-6 Invoices and we got only 1 FIRC copy.if we copy the same FIRC no against the 6 Invoices ,system is not allowing to file the GST refund.How to resolve this. Any solution for this ?