Hi Greg,
We have WTParts connected to are welding CADdocuments (to stay in your example), and other WTParts connected to fixture CADdocuments. On WTPart level, the 'where used' of the welding assembly leads you to the fixture toolings, and eventually other toolings.
To avoid confusion, we created a new softtype for tooling-WTParts, so we can associate an other icon to it.
OK?
Regards, Hugo.