Hi Daniel,
Thank you for the update.
1. The GridGroupingControl default property to expand Group Records in GroupCaptionCell. If you choose the GridControl handle the mouse event to expand and span the the Record Rows manually for each records.
2. The Spanning Cell are created easily through the GridGroupingControl. It Can be achieved though the column sets.
3. The Summary also easily calculated automatically in SummaryDescriptors in GridGroupingControl.
Please refer the modified sample in below link:
http://files.syncfusion.com/support/samples/Grid.Windows/Forums/ColumnSets2.zipThis sample created with you requirement. The Records are spanned with to two rows. The SummaryRow displayed always with Grouping Caption. The Top and Bottom summary color used with different colors in GridGroupingControl.
Let me know if you have any queries.
Regards,
Lingaraj S.