Duck in Triple Plum Sauce

Cut legs and wings from ducks; cut along breast bones and rib cages to remove breast meat; reserve carcasses and giblets. Refrigerate legs, wings and breast meat covered. Make duck stock, using reserved carcasses and giblets. Heat 1/4 cup granulated sugar and 1 tablespoon water to boiling in small saucepan; add lemon juice. Reduce heat to low; simmer, without stirring, until dark brown, about 4 minutes; reserve caramel. Heat oven to 425°. Brown duck, several pieces at a time, and oil in large skillet. Play stuck on rack in large roasting pan. Roast until tender, about 35 minutes. Meanwhile, drain fat from skillet. Deglaze skillet with ½ cup wine; simmer wine until reduced to 3 tablespoons; reserve in skillet. Sauté nectarines and plums in butter and powdered sugar in second largest skillet until glazed on all sides but still firm, about 4 minutes. Transfer duck to serving platter; surround with glazed fruits; keep warm. Drain fat from roasting pan. Deglaze pan with ½ cup wine; pour wine into reserved wine mixture in skillet. Stir in reserved caramel, 2 cups stock and the vinegar. Heat to boiling; boil, stirring constantly, until liquid is reduced to 1 ½ cups, about 5 minutes. Mix plum brandy, liqueur, Cognac and cornstarch in small bowl. Stir into sauce. Cook until mixture thickens and bubbles for 3 minutes. Pour sauce over duck. Garnish with watercress.