Discount

Hi,

At the admin side, we can set discount for category, products and user. Here we set 20% discount for category, products and user at a time. Suppose if a user who is having a discount selects a products with discount. Does the user gets only products discount or both. In the shopping cart the price displayed is price after discount of the product

Here in our case if a user has a discount then the user discount should be calculated not the product discount. How this scenario we can manage?
Is it possible to manage via admin?

Anyone please help me. It is very urgent.

Thanks in advance.