Out of the box, SSAS will always put a Distinct Count in it's own measure group. There are, however, other methods that you can try which may or may not be optimal for your solution. Have a look at the follwing article and read the (linked to) article on all things Distinct Count here: http://www.mssqltips.com/sqlservertip/3043/different-options-for-creating-a-distinct-count-measure-in-ssas/