Sales Invoicing element issue

Hello,

I have an issue with the Pay Early invoicing element that gets calculated based on the Net Total Price (Gross price - discount 1/2 from the lines).

When I changed the structure to No for these discounts, they don't go through the account, but I need to keep these by line, since there are allowances and they post to GL differently 

based on the customization I did into the sales auto journal.

So the customer wants the Pay Early invoicing element to calculate based on the gross total amount before any discounts.

Is there a way to have this through the set up ?

Thanks in advance.