Here is an approach I use in 8.5. It's outlined in the following thread:
Thread767-682614
The basic idea here is that variables that are initialized at a level higher than the level being drilled into become zero when you drill into a level that contains a formula referencing them. (Well the variable value becomes zero in the drilldown tab, not in the report as a whole). So you can test the value of the variable and if it's zero, use conditional suppression to suppress whatever you want in the drilldown tab.
If you need assistance applying the principle shown in the thread, let me know.