Increasing bill rates retroactively

User wants to revise the billing rates (higher rates) retroactively to the first invoice. The invoices have all been paid except the recent one. So what is the best way to accomplish this task? 

One option is to delete the payment, delete the invoice, reissue and adjust the invoice to match the number and date, and then reapply the payments. The only thing you need to avoid is deleting invoices from the closed fiscal year. However, this is a time consuming process as it has to be done for each payment.

Another option is to simply bill the difference via a supplemental invoice: create an invoice for the retroactive rate increase and enter proper memos to document it.