[tim-tim]

I'm not quite sure I follow what you are trying to do. Could you explain it a little more? Maybe post a screen shot of your model tree of the assembly.

Doe the file still open? Depending on how you have the structure laid out, you may have to have the generic assembly open (in memory/session at least) for the part to regenerate properly. Meaning that the part has a dependency on the assembly - which is typically a bad design practice.

Hope this helps.