The above explanation might been confusing. To summarize the issue, End users needs to see
the condition base value ( KONV - KWERT) in the Billing item report. The Sales overview report is based the Billing document items. The data source 2lis_13_vditm needs to be enhanced to add the field KWERT in the report. I do not find a better way to add this field in the report, as KWERT field is from KONV table
A look up between KONV table and VBRP table can be done based on one condition.
( link between VBRP and KONV | SCN ( topics discussed ))
VBRK-KNUMV = KONV-KNUMV
VBRK-VBELN = VBRP-VBELN.
I wanted to check if there is any close approach to add this field in the Billing report ( Request raised as per user ).