[Mathias]

Here's how Shadowrun solved an issue like this:

(This is from the tags.1st file)

  <!-- These are generated as identity tags by condition monitors.  It's only
       here to establish it so the OverflowTo group can inherit from it -->
  <group
    id="Overflow"
    dynamic="yes">
    </group>

  <!-- Since we want to overflow from one condition monitor to another, the tags
       that identify the target need to be identity tags from the same component
       as the things that will use them, so this inherits all those tags.  That
       means that there are no OverflowTo tags on a condition monitor unless
       they've been placed there. -->
  <group
    id="OverflowTo"
    dynamic="yes"
    inherit="Overflow">
    </group>

P.S. Be very careful when working with inherit in tag groups - not having the group to inherit from above the group doing the inheriting in tags.1st is a crash bug.

Also, dynamic="yes" is necessary when adding a tag group definition for something that's an identity tag.