Still no response, we are petty desperate to know how to do this.

In order to delete second row, when another row is deleted on the DeleteRow server side event, please try to do following.

Run InvokeScript method from DeleteRow server side event.

protected void WebGrid1_DeleteRow(object sender, ISNet.WebUI.WebGrid.RowEventArgs e)
{
    if (e.Row.Cells[1].Text == "UnitedPackage")
    {
        WebGrid1.ClientAction.InvokeScript("DeleteNextRow();");
    }
}

Delete row from the invoked script function.

<script type="text/javascript">
    <!--
    function DeleteNextRow() {
        var WebGrid1 = ISGetObject("WebGrid1");
        WebGrid1.GetSelectedObject().GetRowObject().Delete();
            
        return true;
    }
    -->
</script>