or
GridBoundColumn b = new GridBoundColumn();e.DetailTableView.Columns.Add(b);b.HeaderText = "test";protected void RadGrid1_PreRender(object sender, EventArgs e){ foreach (GridDataItem item in RadGrid1.MasterTableView.Items) { if (item.Expanded) { dynamic data = new[] { new { ID = "1", Name ="Name11",ParentID = "0"}, new { ID = "2", Name ="Name11",ParentID = "1"}, new { ID = "3", Name ="Name11",ParentID = "2"}, new { ID = "4", Name ="Name11",ParentID = "3"} }; GridBoundColumn b = new GridBoundColumn(); b.HeaderText = "test"; b.DataField = "Name"; item.ChildItem.NestedTableViews[0].Columns.Add(b); item.ChildItem.NestedTableViews[0].DataSource = data; item.ChildItem.NestedTableViews[0].DataBind(); } }}