Spread 1/3 salsa on the bottom of a 9" x 13" pan. Spinkle with 1/2 cup shredded cheese and chopped onion. Cut each sandwich into 4 6 pieces and arrange on top of salsa, cheese and onion. Add more salsa, shedded cheese, onion and black olives. Pour nacho cheese over all and bake at 350 deg F> for 15-20 minutes. Remove and cool 5 minutes. Top with lettuce, chopped tomatoes, onions, shredded cheese, black olives and sour cream dollops. Serve with nacho chips.