Instead of using the Group presentation style to create a grouped DataWindow object from scratch, you can take an existing tabular DataWindow object and define groups in it.
To add grouping to an existing DataWindow object:
Start with a tabular DataWindow object that retrieves all the columns you need.
Specify the grouping columns.
Sort the rows.
(Optional) Rearrange the DataWindow object.
(Optional) Add summary statistics.
(Optional) Sort the groups.