Sort 'Detail Time' and 'Expense' reports by last name

When running either a ‘detail time’ or ‘expense’ report, after the report is run you can then select ‘staff’ from the ‘group by’ drop down box…

But this sorts the report alphabetically by the staff’s FIRST name.

I feel it would be much more useful for business to have it sorted by last name. Is there a way to do this that I’m missing?

Exporting to excel and then sorting is not a valid option as the manager using these reports has very limited excel ability…. I REALLY need this to be a ‘canned’ report.