Adding a new roof vent (& cutting the hole for it)

Just a random wild thought, assuming you have a vent already somewhere (other than a bathroom) could you add something like a Fan-tactic Vent to an existing vent location. I had one in our bedroom area, found out the vent in the living room had power near it so had one added. What a world of difference having a fan that pulls air in or pushes it out in both vents.