Business relationship manager role and its relation with Project Managers

Question

The business relationship manager is the role that has the main contact of functional users, to help them make the process of understanding their demand and start a project if everything is in place for it; If this role is more focused on the user-facing, 

what should be the interaction between a BRM and a project manager, before the project starts, during its execution, and at the end?

Answer 1

From my point of view, the BDR is responsible for identifying, evaluating, and selecting the best option to be developed from a project, from the business point of view. 

During the implementation of the project, the BDR must be a support of the PM, contributing the business point of view and covering any doubts that may have about the business case. After the closing of the project, the BDR is the one who must evaluate that the results of the project implementation comply with the business objectives set forth in the business case.