Hi Dhana,
Try adding the Model.CoveredRanges in a grid to resolve this. Here is a code snippet to show this.
//Group1#(1,1) cell is CheckBox cell.
this.gridDataBoundGrid1.Model.CoveredRanges.Add(GridRangeInfo.Cells(1,1,3,1));
//Group2#(4,1) cell is CheckBox cell.
this.gridDataBoundGrid1.Model.CoveredRanges.Add(GridRangeInfo.Cells(4,1,7,1));
//Group3#(8,1) cell is CheckBox cell.
this.gridDataBoundGrid1.Model.CoveredRanges.Add(GridRangeInfo.Cells(8,1,11,1));
Please refer to the attached sample for more details.
GroupCheckBox.zipBest Regards,
Haneef