Invoice Payment - always take a discount with Credit memo issue

Hi All

I have an issue that I am looking for an answer.

Invoice Amount $1000.00

Payment terms = 10% net 45

Credit memo related to this invoice is  $- 200 (payment terms are immediate for credit memo)

Net check to be issues to vendor is $800 but we want to take the discount.

When I go to pay this within discount days and want to take the discount I get $100 as discount  where as I am looking for $1000 - $200 = $800 , discount of 10% of 800 is $80.

Is this possible without manual intervention?

Thanks for your help.