How to add the standard drilldown navigation to children ($member.children), but keep the orginal data as well. Preferable, as generic as possible, so I do not have to know what is on the rows at all (might be 1 hierarchy or a combination of multiple).
It's part of the new release (6.6). You can now us $axis in the MDX expression :
$axis +$member.children
and a variant that shows only one drilldown path :
Filter($axis as t, t.currentMember.level_number <= $member.level_number) + $member.children
The result is something like :
After clicking 2006: