How to remove merge cells in DataGrid column when there is no data to show ?

public class GridDecorator
		{
			public static void MergeRows(DataGrid gridView)
			{
			for (int rowIndex = gridView.Items.Count - 2; rowIndex >= 0; rowIndex--)
				{
					DataGridItem row = gridView.Items[rowIndex];
					DataGridItem previousRow = gridView.Items[rowIndex + 1];

					for (int i = 0; i < row.Cells.Count; i++)
					{							
						if (row.Cells[i].Text == previousRow.Cells[i].Text)
						{
					row.Cells[i].RowSpan = eviousRow.Cells[i].RowSpan < 2 ? 2 : 
								previousRow.Cells[i].RowSpan + 1;
							previousRow.Cells[i].Visible = false;
						}						   
														
					}
				}
			}
		}		
<
protected void grdEmployee_PreRender(object sender, System.EventArgs e)
        {
            GridDecorator.MergeRows(grdEmployee);
        }

[IMG]https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpf1/v/t34.0-12/10807134_1510073735912771_856276471_n.jpg?oh=29fcc9f370dd003c51e4dbfbe6561d86&oe=54685F39&p;__gda__=1416058857_e0a47d165095e8a4bcd42da7f130cd59[/IMG]

When I Merge

[IMG]https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpa1/v/t34.0-12/10806900_1510073739246104_499714655_n.jpg?oh=b3ed3642b9a81f58d0d559ce07d6391e&oe=54685201&__gda__=1416056865_b6901eff324666d9d24d856071823026[/IMG]

But I'd like as shown below
[IMG]https://fbcdn-sphotos-h-a.akamaihd.net/hphotos-ak-xpf1/v/t34.0-12/974437_1510073725912772_949911600_n.jpg?oh=8a524564736a3d7b9e5d8d45455cb7de&oe=54674667&__gda__=1416058362_a84fe8a375c2a571e1edd0fb1705762b[/IMG]