Make the Potatoes: Adjust 2 oven racks to the upper and lower thirds position and preheat it to 450°F. On a rimmed baking sheet, toss the cut potatoes (1 1/2 pounds) with 2-3 tablespoons of olive oil then generously season them with salt and pepper. Arrange potatoes cut side down on the baking sheet. Roast in the preheated oven, on the lower rack, until browned and tender, about 20-30 minutes.
Meanwhile, make the chicken; Pat the chicken pieces (2 1/2 pounds) dry with paper towels. Season the chicken generously with salt and pepper. Heat 2 tablespoons olive oil in a large cast-iron skillet over medium heat. When it begins to shimmer, add the chicken, skin side down, and cook without moving until well browned about 3-5 minutes. Turn the chicken over and brown on the other side, adjusting the heat as needed, for about 3 minutes. Remove chicken to a plate and set aside. Leave the oil in the skillet.
Add sausage (8 ounces) to skillet and cook over medium heat, breaking it up into 1/2 inch pieces, until it's browned about 3 minutes. Remove sausage to a paper towel-lined plate and set aside. Remove skillet from heat and pour off all but 2 tablespoons of fat.
Return the skillet to medium heat and add the onions (1), red bell pepper (1), and garlic (6 cloves) and cook, stirring occasionally, scraping up any brown bits on the bottom of the pan, until the vegetables are soft, for 10-12 minutes. Add the wine (1 cup) and continue to cook, stirring occasionally, until most of the wine has evaporated about 8 minutes. Add stock (1 cup), Peppadews (1/2 cup), vinegar (1/4 cup), and rosemary (4 sprigs), and bring to a boil. Reduce heat and vigorously simmer until slightly reduced about 5 minutes.
Add the chicken back to the skillet, along with any accumulated juices, and nestle pieces into the onion mixture. Place uncovered in preheated oven for 10 minutes. Add sausage to the pan, push them down into the onion mixture and continue to roast until the chicken is cooked through about 5-10 minutes, and an instant-read thermometer inserted into the thickest part of the chicken reads 165°F.