Hi aneelchandra,
It seems that you would like to select the max value in each group, right? If I misunderstand, please let me know.
We can use filter to achieve your target, please take the following steps of my sample to you as reference.
1. Add a row parent group without select “Add group header” and “Add group footer”, and
then a new group display in “Row Groups” pane and it named as Group1.
2. Right-click the “Details” in “Row Groups”, and then select “Group Properties”.
3. Change to “Filters” tab, click “Add” button to add a filter like following:
Expression: [SalesAmount] (select a data field which you would like to choose the max value from it)
Operter: =
Value: =Max(Fields!SalesAmount.Value,"Group1")
After completer steps above, you could get the result what you need.
If you have any question, please feel free to ask.
Thanks,
Eileen