xml.dom.minidom appendChild/toxml formatting problem

[Ray]

I have put together some pretty simple code for adding and removing
elements from an XML file, but am having a problem with toxml writing
out the correct format after I have called appendChild on a node.

Here is a snippet:

if (action == 'add'):
   newCluster = domi.createElement(elementType)
   newCluster.setAttribute("Name", elementName)
   elem.appendChild(newCluster)
else:
   elem.removeChild(childElem)

domi.normalize()

configFile = open(self.flist[0], "w")
newDoc = domi.toxml()
configFile.write(newDoc)
configFile.close()

Basically, if I start out with a Cluster that looks like this in the
XML file:
<Cluster Name="RAYTEST">
   <Cluster Name="RAYTEST2"/>
</Cluster>

and then use the createElement, setAttribute, and appendChild lines
from above to add a new Cluster called "RAYTEST3" to the "RAYTEST2"
Cluster, after calling domi.normalize(), domi.toxml(), and
configFile.write(), the XML looks like:
<Cluster Name="RAYTEST">
   <Cluster Name="RAYTEST2"><Cluster Name="RAYTEST3"/></Cluster>
</Cluster>

instead of how I would like it to look, which would be:
<Cluster Name="RAYTEST">
   <Cluster Name="RAYTEST2">
      <Cluster Name="RAYTEST3"/>
   </Cluster>
</Cluster>

Or, if I append "RAYTEST3" to "RAYTEST", it comes out as:
<Cluster Name="RAYTEST">
   <Cluster Name="RAYTEST2"/>
<Cluster Name="RAYTEST3"/></Cluster>

Instead of:
<Cluster Name="RAYTEST">
   <Cluster Name="RAYTEST2"/>
   <Cluster Name="RAYTEST3"/>
</Cluster>


The rest of the XML file retains its original whitespace and
linebreaks.  How can I get this to format the new changes correctly? 
Calling toprettyxml instead of toxml seems to double the whitespace
and linebreaks in the rest of the file.