aktikt, im not sure exactly what you like to accomplish but maybe this helps.
(This applies to Table layouts, havent tested it with Matrix layout)
To make a recursive hierarchy with drilldown in reporting services from an SSAS OLAP cube (with parent-child hierarchy) you:
1. Include the hierarchy in your dataset by drag-n-dropping the parent-child hierarchy in the query designer. Let's call this hieararchy "Employees".
2. Create a table with one column (more if you like to put in values); The first textbox shall contain =Fields!Employees.Value
3. Select the table -> Properties -> Groups tab -> Details Grouping.
4. In the details grouping view under "Group on:" -> "Expression", add =Fields!Employees.UniqueName
4. In the details grouping view under "Parent group:", add =Fields!Employees.ParentUniqueName
5. If you like a document map with the hierarchy, under "Document map label:", add =Fields!Employees.Value
6. Still in the details grouping view, go to the visibility tab.
7. Set "Initial visibility:" to "Hidden".
8. Check "Visibility can be toggled by another report item.
9. Under "Report item:" choose the textbox in the column which you created in step 2.
10. Hopefully, this works. There might be other ways to do this...