Analysis :: How To Get First Row Of Each Grouping In MDX

I have a dataset where I want to find the first dimension member (head, item(0), ...) for each Quarter grouping on my rows.

Example:

2015 Q1 --> Segment A+
2015 Q2 --> Segment B
2015 Q2 --> Segment /

In this case, I want for 2015 Q2 to show "/" only. I managed to get these results by using a calculated member where I take item(0) and than on my rows I group on my Quarter. However, I would like this in my rows using the dimension itself [point of sale].[Segment].[Segment].

I cannot manage to get this done. I either get only 2015 Q2 and not 2015 Q1 output or I get 2015 Q1 and 2015 Q2 but both "B".

Below is my current query that is working when using a calculated member. But I want to have it directly done on the SELECT ON ROWS using the [Stratum history].[Stratum].

[Stratum]
MEMBER [Measures].[Latest stratum per quarter] AS
NonEmpty(
[Stratum history].[Stratum].[Stratum]
,[Measures].[Stratum sales average]
).Item(0).Name
, NON_EMPTY_BEHAVIOR = [Measures].[Stratum sales average]

On my rows :

[Bonus calendar].[Calendar - Quarter].[Bonus quarte]
...

I tried also to use Rank and Rownumber as a workaround because it works on a measure, but the rownumber is not using the group by on the calendar!

MEMBER [Measures].[Rank] AS
Iif(
IsEmpty([Measures].[YTD Sales]),Null,
RANK(
Axis(1).Item(0).Item(
Axis(1).Item(0).Count-1

[code].....