Hi,
Do you mean "before I do the CTRL + F12" and choose the menu option "boarding"? When I call GSX I let GSX calculate it, and override that number in the green bar in the screen. For your information, when do that and I have chosen the ground force operator, I already have 2 cargo trailers. Normaly before the upgrade I have 3, and for cargo aircraft 6 trailers. And than when they return to the airplane with the cargo on the trailers there are only 2 loaded intead of the 6 loaded trailers before the upgrade. Strange, isn't it?