OK, once again, thanks, larry and JFord for looking for solutions with me... I suppose you have already experienced this frustration when you cannot find a solution for a problem and try and try...
Anyway, I will try what you suggest with the other synth, need more time and have now to go to bed in Germany to be fit tomorrow for a new trying session.
Honestly, I dont think it will work... I already have a second synth available in my system, TTS1 from Cakewalk that some people use. It apears in my list of Plugins (BiaB 2016) together with Forte and does not apear either when scaning for new synth under BiaB 2017.
So I expect it will be the same with another synth. But we will see, I'll report tomorrow.
But not everything is bad in life (!), I have just downloaded patch 354 and miracle, the custom tabs are now staying when I re open BiaB, which was not the case up to now (That was the subject of an other post of mine). Thank the Lord!!!
Bernard