Combine sugar mixture, red wine, orange juice, and liqueur in a large container; cover and chill 4 hours. Stir in club soda, oranges, and blackberries just before serving. Serve over ice.
2 bottles cabernet sauvignon (750 milliliters each), 1 cup orange juice, 1/4 cup orange liqueur, 24 ounces club soda, chilled, 2 oranges, thinly sliced (plus additional for garnish), 1 cup fresh blackberries (plus additional for garnish)