So this is what i use the group ability. For example, at a steel mill, you need both coal and iron, and the products need to go to town. Lets say i’m in 1850’s, and there are a lot of horse carriages that revolve in this cycle. I use 3 stations: 1 station for coal, 1 for iron and 1 for product. I set up the lines between the coal mine the iron mine and the steel mill like normal, but then i group the coal station and iron station and i put 1 line for each. It is the same as making different lines with different stations, but the thing is that this feature is used when you have more lines with a big number of trucks/carriages and you dont want your system to fall apart. this is my opinion.