In DLR, on the Vector screen there exists a 're-vector' button.
After selecting a city that has units vectoring to it, clicking this button changes all cities vectoring to that city to vector to a new city of your choice.
This is especially handy when you keep advancing and have to keep changing the vectoring one city at a time (which is a pain). This button allows you to change all 4 cities at once and is very useful.
KGB