So, I'm playing with the Stormlink mod- and I want to use a train with multiple cars for passengers- how am I to do this?

Do I go through each car and set its capacity separately, or do I set the total capacity of all the cars from the engine? Like, if I have three cars- each able to hold 20 passengers, do I set all 3 cars to 20, or do I set 60 from the engine?
Am I able to load all passengers from the engine as well, or do I need to get into each train car to load?
I'm assuming I need to go through each car in the editor and rename the seats- ie one car ends at 20 seats, and I start setting the new seats from 21 on the new car?