Thanks David! And I always thought you could only toggle parts with this field in FTs.
Thanks Andy... not ready to tackle that one yet. I have a fab components that goes through 4 levels of iterations through subsequent levels. And my client is paying for my learning experience here. Unfortunately, it is not just a simple change from one to the next so flexible parts (assembly level) or assembly cuts are not a good option.
How do you guys manage all this -regen- of the FT instances?
I got it stable but it seems every time you touch a part, you have to update the FTs.
I also found some weird happenings as I changed instance names.
No warning; just seemingly arbitrary substitutions.
I am starting to remember why I never use FTs 
Again, thanks. This is a great functionality for the rare occasion I need it.