This paper presents a coordination model allowing managers to define coordination policies in collaborative sessions. Our model allows different collaboration sites to be managed by maintaining consistency of the distributed management actions at the user and collaborative tool levels. The model manages multi-tools and multi-users collaboration sessions. It is based on a partial order representation of interdependencies in collaborative sessions and a logical specification of the required properties. We define three rule classes of coordination sufficient to specify the properties of interest. Our model is used to implement a software component for collaborative session management. We proceed by control of user-level management actions and by automated execution of tool-level management actions.