I would like to be able to print a report for a customer with all invoices with the 'open' state.

I'd print those if one invoice is overdue, with a generic text, company header and send them to the customer.

At the bottom they would then see not only the overdue invoice, but all open invoices.

I have edited my invoice etc so I know how to do some editing, but I don't know how to get started on this entirely new report...