I have an idea to add the ability to send fire units to cover another fire unit's area.
Where I live here in Vancouver B.C. Canada this is what they do.
If for example Engine 18 gets a call and has to go out to attend and they will stay at the call for a long time, the dispatch would get Engine 9 to go to Station 18 and cover 18's area. This called Fillin/Deckin.
Just thought it might be an idea to add to the game.