Regular Monthly Sales between Corps

Hello. Is there a way, for example, my Corp A to sell X number of goods to my Corp B every month without me having to enter it every month? I am trying to set corps to support each other but they only seem to be able to sell on the open market. Thanks for your help.

Try to sign contract between them. I'm not quite sure did I actualy done it in this way but corp A must offer X number of goods in contracts and corp B must accept it.