HPorter

I know that the spirit of the contract agreement between Prime and sub, that the PM of the Prime communicate directly and only with the PM of the subcontract. I remember a FAR that also states what the communication is for Prime and sub, but I can't remember specifically. The Prime PM thinks that he can circumvent the sub PM and speak/task the other sub contractors, because it is not specifically written in the TA or Contract agreement. How can the subcontractor PM enforce communications on the Prime PM?