Preheat the oven to 200°C.
Remove duck wings and chop giblets and heart, reserving the liver for later.
Sauté carrot, celery, garlic, and sage in oil, then brown the duck trimmings.
Deglaze with sugar and vinegar, add wine, cover with 600ml water, and simmer for 1 hour.
Bake potatoes for 45-60 minutes while boiling swede and parsnips separately until tender.
Blanch cabbage leaves for 5 minutes, then refresh in cold water and squeeze dry.
Sauté onions and garlic in 100g butter with cabbage until soft and seasoned.
Rice the cooked potatoes, swede, and parsnips separately, mixing each with remaining butter and seasoning.
Score duck skin, season, and roast on a trivet for 45 minutes, basting with rendered fat.
Brush duck with marmalade and roast for another 40 minutes while basting.
Rest the duck, then roast legs for another 15 minutes if juices do not run clear.
Strain and reduce the stock by half, skimming fat to reach a gravy consistency.
Layer potatoes, swede, onion-cabbage mix, and parsnips using a ring mold.
Fry chopped liver in butter, carve breasts diagonally, and add liver to the gravy.
Serve duck slices and legs with vegetable stacks, adding orange segments to the gravy.