I have a method which returns some xml in a memory stream

private MemoryStream GetXml()
        {
            XmlWriterSettings settings = new XmlWriterSettings();
            settings.Indent = true;

            using (MemoryStream memoryStream = new MemoryStream())
            {
                using (XmlWriter writer = XmlWriter.Create(memoryStream, settings))
                {
                    writer.WriteStartDocument();
                    writer.WriteStartElement("root");
                    writer.WriteStartElement("element");
                    writer.WriteString("content");
                    writer.WriteEndElement();
                    writer.WriteEndElement();
                    writer.WriteEndDocument();
                    writer.Flush();
                }

                return memoryStream;
            }
        }

In this example the format of the xml will be:

<?xml version="1.0" encoding="utf-8"?>
<root>
  <element>content</element>
</root>

How can i insert a new element under the root e.g

  <?xml version="1.0" encoding="utf-8"?>
    <root>
      <element>content</element>
      ----->New element here <------
    </root>