Ok I got it; then how do you explain that for Zurich which I acquired from FSDreamteam, I have also the same problems: the parking numbering is completely different from what I get in Flightsimcommander (FSC) which requires when you add a new addon scenery to update its database via its manager software and uses for that the scenery file which is located in Winwows 10 pro under the following path:
C:\ProgramData\Microsoft\Fsx\scenery.cfg
What I do every time after activating the scenery in FSX library, I first reinitialise GSX with the GSX live update and run the FSC database manager (as far as this second software is concerned, FSC refuses to run unless you have updated its Database). Even if the scenery is not located on the drive under FSX \Addon scenery, the program finds it as it scans scenery.cfg where the new addon is always present because you have activated or it has been by the setup of the addon provider.
I suppose that with addons like the Zurich one, you have the full airport installed with all its parkings set up, which overide the stock airport and anyway for with Ray Smith's addons he always reminds you to delete all previous files you may setup before, OBJ files included located in FSX Global scenery.
Up to now I have encountered this problem with very few (less than 5) addons scenery. In each case either the aircraft is not positioned in the correct orientation on the parking, or the number in GSX is not the same than in FSC. In both cases GSX considers that you're on a parking and asks you to choose one and position it there either by taxing to it or warping the airplane to the parking.