I have added a custom Link field (via Relationships) to the Accounts entity called "paymentTerms". This Link field maps to a custom entity called "PaymentTerms" which specifies the accounting payment terms for a specific account.

I've added a custom Link field (via Relationships) to the SalesOrder entity which also maps to the PaymentTerms entity.

What I would like to do is, when a Sales Order is created and an Account is selected, as well as the shipping and billing addresses being copied straight across, I would also like the default payment terms from the Account copied across. How could I achieve this?