title: Adding variable number of elements to xml file using wix
body: <p>We use wix to modify xml during install. We need to add a list of xml elements to a file.
  Example list:</p>
  
  <pre><code>&lt;Item&gt;
      &lt;Address&gt;some@address.com&lt;/Address&gt;
  &lt;/Item&gt;
  &lt;Item&gt;
      &lt;Address&gt;someother@address.com&lt;/Address&gt;
  &lt;/Item&gt;
  </code></pre>
  
  <p>Now we want to add this to an xml file under a specific node.</p>
  
  <p>How can we do this in wix?</p>
  
  <p>We already use XmlFile to modify other parts of the xml, can we use this or do we have to use a custom action?</p>