Not good news i'm afraid. as long as there's food in the area, they are likely to stay, and when they have their young, the dominant male can get just a little bit aggressive, and will take on, and beat a cat. If you can find out exactly where they are nesting, they are very sensitive to smells, rags soaked in a very strong disinfectant should ppersuade them to move, you may have to repeat, and, of course, they may only move to a different area nearby, especially if there's a nut tree cloe. (Oak, Walnut, Beech etc).