AR Payment Terms - Discounts

For our company when creating invoices (thru an upload process), the payment terms default into the invoice from the customer master. We have hundreds of customers and many unique payment terms associated with these customers. Some customers have discount terms and some do not.

For the customers that have discounts in their payment terms, We have certain situations where we do not want to grant these customers a discount, such as: Lines on the invoice for Freight, Lines on the invoice that are negative and Invoices that are a Document type 'RM'.

Without doing a manual change of the invoice or Invoice lines (This would be too much of a manual effort), is there a way to have JDE not create a discount available for these situations and still allow the Payment terms to default from the customer to the Line Items on the Invoices?