I have a contractor to redo my concrete steps. We made an agreement to replace the entire steps.Now he is suggesting to pour over the existing steps foundation, adding about 4" over the entire foundation.Some of the steps have small cracks and in some places the concrete is chipping away. Cracks are alone the side of this foundation and at the top of the steps a long crack is where the step connects to the house.

My question is okay for him to pour concrete over this foundation or rebuild the entire steps over again?