Ok, thanks for all the help. I have another question or two.
At the moment, I am supplying a coal mine with coal from two other mines. Soon, I will make a third one supply it too.
i.e. Mine A and Mine B transfers to Mine C, Mine C transfers to Mine D, Mine D transports to Power station.
As you can tell, Mine D gets A LOT of coal and I think its time to expand Mine D's station with more platforms and have more than one train transport to the Power Station. Before, I have done this by building a one-platform station adjacent to the existing one. However, it doesn't look very nice or uniform when half of the station has a shelter and the other half doesn't.
Could I simply remove the station and replace it with one that has more platforms? Will it mess with train orders? I tried to do this but apparently the authorities wouldn't let me build the station. Any help would be grately appreciated.