Hierarchy handling in DAX is not very easy, due to the fact that hierarchies, unlike it was in MDX, are not first-class citizens in the DAX world. While hierarchies can be easily defined in the data model, there are no DAX functions that let you access, for example, the parent of the CurrentMember. Well, to tell the truth, there is no concept of CurrentMember in DAX either. That said, there are several scenarios where it might be useful to handle hierarchies in DAX and, in this post, I am going to show some techniques to make them work in a clever way, starting from the basics until we reach a good level of hierarchy understanding in DAX.
Read more at http://www.sqlbi.com/articles/clever-hierarchy-handling-in-dax/.