In a large 6 quart Dutch oven or similar size pot, melt butter over medium heat. Add onion, cooking for 5 minutes or until softened and beginning to brown. Add garlic and fennel seed cooking for 1 minute longer.
To the pot add chicken, pulled pork, brisket, crushed tomatoes, diced tomatoes, chicken stock, mustard barbecue sauce, vinegar barbecue sauce, Worcestershire, seasoned salt, black pepper, cayenne, lima beans, corn, thyme and bay leaves. Mix to combine.
Bring to a boil then immediately lower the heat to low. Cover and simmer for 50-60 minutes.
Uncover and check thickness, use two forks to shed chicken further. Add additional stock to thin or add tomato paste to thicken.
Remove bay leaves and thyme sprigs then serve hot with cornbread and hot sauce, garnished with additional thyme, if desired.