Append/Replace XML section? [resolved]

[Shurijo]

How can I append or replace a single section within my XML file?

Currently, I am having to save the entire XML file when I make changes to my data. But I would like to be able to reduce the time, by only saving 1 section of the XML file.

I would like to be able to save info to the user settings, without saving the entire user and data items, etc.

...
<user>
   <settings .... />
</user>
<data>
   <item ... >
       ....
   </item>
   ...
</data>
... 

Reference: (This is how I am reading/writing XML)
Read XML from a file
Write XML to a file

thanks,