Our customers pay in a variety of ways - payment with order, on account, by return, via DD...

We have different Invoice Layouts for differing payment methods and consequently different email wording to send with the relevant invoice.

I would like to be able to link the 'correct' invoice layout and email wording to the customer so that it is set up once and not subject to user error (i.e. sending a customer a payment due invoice when they have in fact already paid).