XDocumentAddElements

            var headers = new XDocument
                (
                new XDeclaration("1.0","utf-8","yes")
                );

            headers.AddFirst(new XElement("Data"));

            headers.Root.AddFirst(labHeader);

            headers.Root.Add(orderHeader);
            headers.Root.Add(orderSubHeader);

            headers.Save("C:\\Zin\\Test.xml");

            Debug.WriteLine("");