Converting a sales order to Invoice, but changing the customer on the invoice

Converting a sales order to Invoice, but changing the customer on the invoice

Hello! My quotes and sales orders are usually recorded to the end-user account. some times I need to invoice a different entity. I would rather not have to change the "Account" on the sales order because that info gives me actual purchase history.  Accounting wants the sales order in the Account that should be invoiced. 

When I take a sales order and convert it to an invoice, it doesn't let me change the account to the billing account.  Probably because the account on the invoice should match the account on the Sales Order. 

How do people handle this? is everyone changing the sales order to the different accounts who wrote the sales orders?  or How do you invoice another responsible party and track sales by end-user? 

Thanks!