Hi Vamshi,
* Dynamic items are flowing into RRB i.e, [DP91] when WBS element is assigned to Sales Order item in Account assignment tab.---Yes its correct
* Except Costing sheet assignment at "Control tab" in CJ20N, there is nothing much i could find in WBS Element. one interesting observation is the Costing Sheet which is assigned at DIP profile at "Sources" is different from the assigned Costing sheet in WBS Element.----you can select cost element etc for capturing costing data in DIP profile. whole processing is based on DIP Profile config.
* But both costing sheets having Calc Base, Qty/% Overhead are sharing cost elements belong to same cost element group.-----i think you dont need costing sheet in DIP Profile.
you can first set DIP Profile correctly and verify in ODP2.
if you are selecting wrong field to be captured than DIP Profile will calculate wrong/ wrong behave.
thanks
Sunil