apply coupon to orignial price, not discounted price

-- HikaShop version -- : 4.0.1
-- Joomla version -- : 3.9.1
-- Browser(s) name and version -- : Firefox 61.0.2

I would like to have a coupon applied to the original price before the discount is applied. In other words, if the product has a discount, ignore the discount and apply the coupon. It seems from the documentation that you can set it to ignore the coupon is the discount applies, but I want the opposite.
For example:
User group XYZ gets a 20% discount for certain products. This discounted price is shown both on the product page and in the cart.
We are also doing a promotion for 50% off the ORIGINAL product price for certain products for XYZ users.
So if a product is $100. When the user logs in, the price on the product page and in the cart will show the 20% discount applied, $80. If they enter the coupon code, we want the total to be $50, not $40.