You mean you have something like:
Group 1
Headers Name DOB Gender
Details John 1-1-50 M
and you want the "Header row to appear only on when you drill down on Group1?
You can add a GH1b - create your headers there and conditionally suppress that section as: drilldowngrouplevel=0
or another variation of that depending on your group levels and needs.
Or you can add a detail section B and add your data field there,
put your "headers" on details A,
add a counter field (variable or running total) into details A that resets on each group change and conditionally suppress details A section where the counter>1