Right, Thanks @OndrejTrhan
That can be a solution (I was aware of) for one model though that solution was not needed before I upgraded to ZBrush 2025.1.1 from ZBrush 2022 something. I guess I have to reverse to a former version (but which one?) of ZBrush since I usually have dozens of FACS to process.
Or ask for script.
I am sure a good solution can be designed. I keep you updated.
Thanks for your time Ondrej.