In SSAS Parent-Child-Hierarchy how to use MembersWithDataCaption

I have a parent-child-hierarchy with MemberWithData=NonLeadDataVisible. I tried different values for MembersWithDataCaption, but I always get name of datamember equal to name of inner node. I am using SSAS 12.0.5538.0. Questions: - Where to set MemberWithDataCaption, Parent or Key? - MemberWithDataCaption is a formatstring, how does it work? For simplicity I set the value "parent" without effect (after deploy and process). - What are the conditions for MemberWithDataCaption to actually work?