In a small bowl, pour enough boiling water over cherries to cover. Let stand for 5 minutes; drain. Meanwhile, use two forks to pull chicken meat off the bones and shred in large pieces. Discard bones and skin. Measure 2 cups chicken pieces and place in a medium bowl; set aside. Cover and chill remaining chicken for another use.
In a screw-top jar, combine the 1/2 cup balsamic vinaigrette and orange juice. Cover and shake well.
To serve, arrange lettuce on 4 dinner plates or on a platter. Top each with mushrooms and grapefruit sections. Arrange chicken in center of each salad. Sprinkle salads with cranberries and sunflower seeds. Drizzle the dressing evenly over the salads. Makes 4 main-dish servings.