Hi Sam,
To change the order of the columns in Gridgrouping control you can make use of the following code
this.gridGroupingControl1.TableDescriptor.VisibleColumns.Move(0, 1);
Here is a sample for your reference,
Sample:
http://websamples.syncfusion.com/samples/Grid.Windows/F67991/main.htmKindly take a look and let me know if this helps.
Regards,
Ajish.