This is part of the answer.
Also, almost every single day I use two computers (for various reasons) to work on the same Ableton Live 9 Projects that include many Reaktor instances.
The Projects are shared between the two computers using DropBox.
When loading a Project that was last opened on the other computer, I have to locate the Reaktor Ensembles that were previously saved with the Project, as proposed by the following window.

With Reaktor 5, I have to show the path only once for all Ensembles, thanks to this second window.

Unfortunately, the second window does not appear when using Reaktor 6.
This means that I would have to locate between 20 and 40 Ensembles separately (depending on the Project) each time I open a Project that was last opened on the other computer (several times a day).
One day, I read the user manual and searched the forums for a solution to this problem, without success.
Until today I didn’t ask Native Instruments about it, as I’m fine with Reaktor 5 most of the time (I only use Reaktor 6 to see how builders have implemented such and such function, to find inspiration or a solution to a specific problem).
And, honestly, I’d prefer to continue using Reaktor 5 as long as possible.
I’m comfortable with the interface and do not need the extra features offered by Reaktor 6.
Anyway, if anyone has a trick for showing the path only once when using multiple instances of Reaktor 6 in Live 9, I’d be happy to know, as it would be useful to me from time to time when I reverse engineer a Reaktor 6 Ensemble.
It’s quite possible that there is an extremely simple solution that I completely overlooked !
