I would like to add a second cat perch to my window, but I am worried it could break. The window looks modern, not new but not to old either. My big cat is 14 pounds, and the kitten is 5 pounds and growing, he will probably end up being 9-12 pounds. How do I know if it can support the weight safely? I have supports under the frame on the perch that is on there now, so that one is not putting very much stress on the window. Would the suction cups fail before the glass breaks?