Incompatibility level- Pricing modifier.

 Hi Experts,

Could any suggest on the below requirement.

I have a current pricing modifier that applies pricing for labels that the distributor can request.  I have about 10 customers that should not be charged for these labels so I wanted to create an incompatibility level to use on this current pricing modifier as well as a new no charge modifier that I will be creating.  How do I create a new incompatibility level? 

Thanks.