Dave,
I just uploaded the file "MF_VCpot.zip".
I got tired of trying to allocate floating net names to different pots.
I chose the pin name as "PC", because it is the Pot Control pin.
Feel free to Look over the files and see if it will help with your "Fz" issue.
I think that it is easy to apply net names from the top level to subcircuits.
Mike