AA 26 speaks of them to “assist the apostolic work of the Church either in the field of evangelization and sanctification or in the charitable, social, or other spheres …” and recommends the cooperation of priests and Religious.
While preserving the proper character and autonomy of each organization, these councils will be able to promote the mutual coordination of various lay associations and enterprises. Councils of this type should be established as far as possible also on the parochial, interparochial, and interdiocesan level as well as in the national or international sphere.
AA26 also called for the establishment of a special secretariat, which was done, to “serve as a well-equipped center for communicating information about the various apostolic programs of the laity, promoting research into modern problems arising in this field, and assisting the hierarchy and laity in their apostolic works with its advice.”
I don’t know if this secretariat has ever had a lay person in charge. Maybe Rock or a few others would know.
The various movements and projects of the apostolate of the laity throughout the world should also be represented in this secretariat, and here clergy and Religious also are to cooperate with the laity.