Our local shelter posted on facebook a cool idea: take an igloo cooler and cut a hole in the side just big enough for a cat to fit through. Fill with straw. The insulation plus that cats body heat warm the cooler up and keep it warm enough for cats to survive cold winter nights.....maybe place it in the area the cat is in and see if she moves them????
You can also use two plastic totes (with one being slightly smaller then the other). You place a layer of the insulation board between the two totes. Do the hole and straw thing, same as the cooler. Use straw because it works better then blankets.