Most modern tractors and combines have the ability for a second passenger and of course any on-road vehicle such as the in-game pickup truck certainly has capability for more than one passenger.
The software already knows the XYZ coordinates of others in multiplayer so it's just a matter of ***adding some code**".
See the feature working like this: First person to enter a tractor, combine or pickup/car is the driver, just like FS19 works today. A second person enters the vehicle and they are automatically the passenger. A pickup truck would have the ability to provide spots for four multiplayers while a tractor or combine would just be two.
