Editing an invoice after payment has been made

Editing an invoice after payment has been made

Hi. I'm wondering if you could help with the following:

I have a customer that wishes to pay for an invoice (hire of equipment for an event next month), however they may add to the equipment they have ordered between now and the event. If they pay for the invoice now, can I edit it later (if they choose to add more hire items) and then resend them the updated invoice so that they can pay the difference?

Thanks