Melt margarine in 10-inch skillet over high heat. Add chicken; cook about 3 minutes, stirring occasionally, until outside turns white. Stir in water, 1/2 cup milk, Gravy Mix, frozen vegetables and frozen potatoes. Heat to boiling, stirring occasionally. Pour into ungreased 2-quart casserole. Drop dumpling dough by spoonfuls onto chicken mixture; sprinkle with parsley flakes.