Exclude MAP vendors in Discounts

We carry a number of vendors that require us to adhere to MAP (minimum advertised price). We run regular discounts by category and need to be able to exclude specific vendors from these discounts. Is there a way to apply discounts to categories and add a second filter that excludes selected vendors?

rpouvreau wrote:

I think you can assign a new role for these vendors and add this role (ie. DiscountedVendot, ) as "Required customer role" for getting the discount.

Note: Don't remove vendor role from them.