Is there a way that I can block some customers from viewing a category of articles?
We want all the customers to be able to view all the knowledge articles except for Category A and Category B. We want to be able to assign certain customer's to view all categories including Category A and Category B.
Is this possible? Adding the customers to groups would be great too if that's possible.
Not sure that would be the best option. You would incur the cost of additional Users. The Restricted User Role control access by using watchlists. You would have to test this and those people obviously would be logging into the Service Desk and not the Customer Portal.