Getting updated addresses onto Sales Orders/Invoices

We create sales orders, up to 1 year in advance, as a way to schedule future invoices.

The problem is that sometimes the company's address changes in the meantime. We update the address on the customer record, but this update does not get automatically carried back onto existing sales orders.  And the address that is on the sales order is the one that ends up on the invoice.

Does anyone know how to make the address update work automatically?

I have found a way to go onto the sales order and update the address there, but this requires about 6 extra steps for each and every sales order.  We need a faster and/or automatic process.