you can create a calculated field as:
if [commission type]='AA' and Buyer ='Kendra' then 'Commision'
else 'Trading' end
now can use this column for grouping your data accordingly.
Thank you for your answer.
But how should I group the rest of the commission type?
In the same way you can add 'ifelse' clauses for other commission type if your grouping conditions are static..
If your conditions are not static then we need to find out some other solutions