Hi Karl,
Thanks for your interest in Syncfusion Products.
The tablecontrol of a table can be retrieved through its name through the following code.
GridTableControl tc = this.gridGroupingControl1.GetTableControl("MyChildTable");
Through this object, you can implement any settings for that particular table.
For grouping, each table must have its own groupdroparea. By default, the groupdroparea get added to grid only for the main table. For child tables, it has to be added explicitly with the following code.
this.gridGroupingControl1.AddGroupDropArea("MyChildTable");
Here is a minimal sample for your reference in which these were illustrated.
http://files.syncfusion.com/support/samples/Grid.Windows/7.3.0.20/F88805.zipRegards,
Rajadurai