Grouping does more than sort. What you are descibing seems more like a question of how to group data at Group2 but it is hard to tell based on the limited information.
Only way I can think of that might come close to what you are decribing is with subreports that would replace G2 and G3 but again hard to tell without knowing the data and what you are trying to do with it.
That being said I still think you want to look at it more along grouping at level 2.
Edited by DBlank - 26 Feb 2010 at 7:02am