For users of GSX, we have created custom GSX Profiles for each of the F28 variants.
With the release of the F28 Professional "Version 2" update, the GSX profiles are now included within the product itself and will take effect automatically upon loading the aircraft in the simulator.
In order for GSX Seated Passengers to appear inside the aircraft's cabin, each of the F28 variants must be selected in the FSDT Installer > GSX > Config menu. It may be required to deselect and reselect each of the F28 variants after reinstalling/updating the product.