Matteo,
I would suggest watching the following videos on VI-Pro. You can expand the "info"button to the left of the video, in order to view a specific chapter.
- Overview (how to use cells & matrices generally)
- Stacking Instruments (how to create your own organ registrations)
- Features & Gadgets, Chapter: Enable/Disable Cells (recalling your 'registrations' for a particular piece)
That should answer your question, within the approach it seems you are trying to utilize. Personally, I prefer creating a unique midi channel per stop/patch. I can then easily use a CC controller or keyswitch to disable the stop by switching to a cell I've left empty. Each instance has two cells, one with my stop and an empty one.
Either method words. One is live, more tedious to build, and not the easiest to manage in the DAW... but effective and not overly difficult IMHO. Creating presents is easier to do quickly and probably easier to work in, though less flexible. We've heard a hint of something coming to help here. It may take time, but it will certainly be worth it. 😊
Hope that helps to get you started!
Sean