Consolidate building contracts?

Each time the cargo center that I am using is enlarged I have to sign a separate new contract to make use of the enlarged facility. If this continues it will become tedious allocating the routes to the various contracts.

Is there some way to consolidate all the contracts into one? Or would I have to cancel all the contracts and take out a new contract? Alternatively is there some way to automatically extend the contract when a cargo center is enlarged?

No reply - well. I cancelled the existing contracts, now I have to wait till they all run out until I can make one new one.

AFAIK, that was the only thing you could do.

In fact it needs even more work - the party offering the building has to cancel his original offer and make a new offer for the expanded building.