In a small bowl mix the soups, and the milk set aside.
Melt margarine or butter in a medium saucepan over medium high heat. Add onion and chili powder, and sauté until tender. Stir in the chicken, diced tomatoes and green chilies, black beans, and 3 tablespoons of the soup mixture.
Cook and stir until heated through.
Spread 1/2 cup of the soup mixture in a 9x13 inch baking dish and 1/4 cup into a 8 x 8 inch baking dish. Spoon about 1/4 cup of the black bean mixture and about 1 tablespoon of cheddar cheese down the center of each tortilla.
Roll up tortillas, and place, seam-side-down, in the baking dishes. Spoon remaining soup mixture on top, and sprinkle with the remaining cheese.
Bake 25 minutes in the preheated oven, or until bubbly and lightly browned.