Can we create Security Roles for eBill PAyment that are applied based on the Customer SETID?

We are implementing eBill Payment. We have Customer Contacts that represent Customers in multiple SetID's (equivalent to Business Units since Customers are defined separately to each Business Unit by using the BU SETID).  In one of the BU's, we want the Customer Contact to have the ability to pay for Open Items, while restricting this in all other BU's.  We have created two roles to assign to Customer Contacts, one with Payment Capability and one without a Payment Capability.  In the one without a Payment Capability we have not used Permission List EPEB2000, and modified Permission Lists EPEB1000 and EPEB4000