I realize this is very old, but wondered if you still used this customization, and if so, I wondered if I could see a screen shot of how you are using it? It seems like a way to list spare parts which is something I am investigating.
Windchill 11.0 M030 CPS08
Sorry for the very delayed response to this, yes we still use this functionality, but it is less of a customization these days. We now use a configured link between the WTPart masters, this has been rebranded as a "companion part" link to avoid confusion with Releated parts.
We do still have our own user interface to create/maintain those relationships, as we have some additional business logic around their creation. Plus given that these links are to the part master, access control is hard to manage, so we control that in our user interface.