Hi Salhi
You can assign your own reports in the report group in Transaction code GR52.
You can add reports by clicking on configure button and can add or assign your drill down reports.
You can assign any of the following.
BB | Report Portfolio |
| BW | BW Query |
| QU | SAP Query |
| RE | Drilldown Reporting |
| RT | ABAP Report Program |
| RW | Report Writer |
| TR | Transaction |
Usually it is better to create Z Report group rather than changing standard report groups.
Hope this helps.
Regards
Rahman