You can do this now when you're part of a common market.
Go to the common market menu, select Contracts>Accept contracts for your corporations needs.
Below the list of corporations, there's a list of choices to accept only local, only common market or both.
If you select only local, your corporations will close all the contracts they can with local corporations. You can then do a second run where you also accept common market contracts.
Note: the above only works if you have also set your corporations to offer goods on the local or common market. It's the same main menu menu, one step lower.