The first is some parking spots with the second containing all the Gates.
GSX doesn't support such configuration.
The AFCAD used must be self-contained and GSX will only use data from a single AFCAD. This means, even if you could alter the choice of the AFCAD in use (by placing the AFCAD in areas with an higher priority), the one used must contain everything needed for GSX to be working, so all parkings, gates and taxiway layout, will only come from a single file.