Hi
If I understood it, you want to figure out it as a group condition but to apply it for items. It's difficult to solve it without to reproduce it, but I'd try with VOFM formula base subroutines (maybe in the pricing procedure) or in the condition (V/06), you have the chance to handle it with VOFM subroutines in scales.
My apologies, but now I am without a SAPgui and I am remembering the screen for V/06.
I hope this helps you
Regards
Eduardo