Beat cake mix, oil, remaining water and remaining eggs in large bowl with mixer until blended. Add sour cream; mix well. Pour half the cake batter over caramel syrup in pan; gently spoon milk mixture over cake batter. Cover with foil sprayed with cooking spray. Place filled pan in larger shallow pan. Add enough water to larger pan to come halfway up side of flan batter-filled pan. Pour remaining cake batter into separate 9-inch round pan sprayed with cooking spray.