There are other brands too. The azek ones have a textured finish which you may not want. For simplicity, I'd just go get 1.5" wide, smooth pvc exterior trim boards. Then miter them around the existing brick mold. You could glue it to the brick(use something exterior rated with instant grab hold time) and shoot a few finish nails through it into the existing brick mold. I think taking it apart is opening a can of worms. It's doubtful anyone but you will notice the difference anyway.