You may run across small agencies that will not work with managers. Generally, that is because they are small enough to provide them with the services a manager already provides. The larger agencies will work with managers because managers can stay on top of all the minute details and this saves the large agency both time and effort.

When you are signed to an agent and a manager, generally appointments go through the agent and funnel to the manager and then to the client, where they are discussed. Managers will generally provide information to the agent regarding people in the industry that are impressed with their client, thus helping the agent secure appointments where there is a mutual connection. When negotiating, the agent generally receives the offer and presents it to the manager, who will then confer with the client. Then the manager will work with the agent to come up with an acceptable contract, or if all parties are in agreement, walk away from the offer presented.

I believe the manager has the most uniquely important role in this trio because he/she best knows the client's desires and needs from being involved in the actor's day-to-day business and personal activities. A manager also usually has an established relationship with any agent who has been brought on board. Of course, not all of these "trio" relationships turn out rosy, but I feel with excellent communication from all involved it can be a rewarding arrangement.