Is there a way to group results returend by Descendants function?

[kpa]

Here is my query:

select Non Empty Crossjoin({[Measures].[Duration (m/h)]}, {[Tester].[All testers].Children}) ON COLUMNS,
NON EMPTY Descendants([Manual test].[All manual tests], 3.0, SELF) ON ROWS
from [runs]

Which returns lowest level of 'Manual Tets' Hierarchy in a way like:
Tester 1 Tester 2
Manual test 1 10 20
Manual test 1 20 30
Manual test 2 30 40

Is there a way to group and sum 'Manual test 1' in one row?
Thanks in advance.

[Island1]

Would you mind restating this using the Adventure Works cube? That will allow us to get you a working example as an answer.

Many thanks!

Bill