Into your slow cooker, stir together the olive oil, red wine vinegar, prunes, olives, capers with brine, bay leaves, garlic, oregano, salt/pepper, 3 Tbsp. brown sugar, and wine. Place the chicken thighs into the pot. Cover and cook on high for 1/2 hour. Reduce to low and cook another 4 hours or until chicken is very tender. Taste the broth and add a little more brown sugar if needed and season if necessary. Transfer to a bowl or plate directly. Scatter parsley over the top.