It’ done. it was already configured in asio link pro tool, and in Audio Settings I did unchecked link 3 and 4 but I did not realize that these were drop-down menus with 60 left checkboxes to untick one by one 
I have just replaced my Steinberg UR22 with an RME Babyface - without regret. 
The problem is the same again: in all the gigs and rackspaces, I was using audio input 2 and now it’s input 4.
Asiolink works fine but, maybe I am too demanding or obsessive, I wanted to avoid using additional applications to manage this.
The alternative solution I have chosen - more radical but quick and simple - was to do a batch conversion of all gig and rackspace files, using Notepad++.
The operation took less than 10 seconds to modify the 191 files concerned. It sounds stupid but I feel lighter this way, using only RME asio driver.