Collective Invoice

Dear Experts

We are having a scenario wherein there are 5 or 6 individual invoices created for the buyer in a month.At the end of the month the buyer needs a one single invoice (i.e. it should combine all these invoices with all individual invoice numbers into a single invoice).

So in all we need the individual invoices (for our records) and a SINGLE INVOICE created with all individual invoices for the buyer also.

How can i map this?