title: Append XML string block to existing XmlDocument
body: <p>I have an XmlDocument that already exists and is read from a file. </p>
  
  <p>I would like to add a chunk of Xml to a node in the document. Is there a good way to create and add all the nodes without cluttering my code with many .CreateNote and .AppendChild calls?</p>
  
  <p>I would like some way of making a string or stringBuilder of a valid Xml section and just appending that to an XmlNode.</p>
  
  <p>ex:
  Original XmlDoc:</p>
  
  <pre><code>&lt;MyXml&gt;
     &lt;Employee&gt;
     &lt;/Employee&gt;
  &lt;/MyXml&gt;
  </code></pre>
  
  <p>and, I would like to add a Demographic (with several children) tag to Employee:</p>
  
  <pre><code>&lt;MyXml&gt;
     &lt;Employee&gt;
        &lt;Demographic&gt;
           &lt;Age/&gt;
           &lt;DOB/&gt;
        &lt;/Demographic&gt;
     &lt;/Employee&gt;
  &lt;/MyXml&gt;
  </code></pre>