Group Discount malfunction in Admin Dashboard

Hi...I offer a discount on a couple of products to a particular customer group. These customers have been buying this product and the discount is applying properly to their order however, if I have to go in their order after they buy it and make a change the group discount is removed and I can't seem to adjust the price to put the price discount when within the customer's order. These customers are also using a coupon for free shipping and I can't use two coupons at once in the admin area. Why isn't the group discount staying on the order and why can't I manipulate product price in the edit customer order area? Am I doing it wrong?

I can't find any other way around this. Please help! Version 2.2.0.0