My brain is hurting

Hi all

I have the following xml structure.  To paraphrase quickly, I have users
and groups, each user or group has a parent group defined - except for
group 'default', which is always top of the tree.  I have settings for
each user and group.  Each settings node can be specified as 'use
settings from parent group', or 'specify my own settings'.

<root>
  <settings>
    <user name="chris">
      <usegroup="1" />
    </user>
    <user name="phil">
      <usegroup="0" />
      ...
    </user>
    <group name="default">
      <usegroup="0" />
      ...
    </group>
    <group name="othergroup">
      <usegroup="1" />
    </group>

  </settings>
  <users>
    <user name="chris" parent="othergroup">
      ...
    </user>
    <user name="phil" parent="othergroup">
      ...
    </user>
    <group name="default" parent="">
      ...
    </group>
    <group name="othergroup" parent="default">
      ...
    </group>
  </users>
</root>



I am trying to write a transform which, when given a group name as a
parameter, will output a list of usernames which will use that group's
settings.

Example, if parameter 'group' == default,
it will output "chris" in the above example

However, my xsl skills are nowhere near good enough for this.

Does anyone have ideas for me?

Regards

Chris