You will not be able to use the SummaryRow to do this, since the it runs a statistical function on all the rows (e.g. sum, average, mean, etc…). It cannot sum a part and substract another part.
You will need to create you own calculating row. Basically, add a ValueRow in the FixedFooterRows of the grid, then in an event monitoring changes to your SummaryRow, like the SummaryCell.ValueChanged event, get the values of the total of each group, substract them, and display the result in the ValueCell.
Imported from legacy forums. Posted by André (had 3580 views)