Start the grill, allowing it to reach a temperature of 250 degrees, or pre heat the oven to 350 degrees.
In a large skillet, cook the sausage and onion over medium-high heat for 5 to 6 minutes until the sausage is browned and the onion softened. Add the pork and cook for 2 to 3 minutes longer until the meat is just heated through. Set aside. In a large bowl, combine the pork and beans, sauce, molasses, seasoning mix, and liquid smoke, if using. Stir well and transfer to a deep casserole. The casserole should be large enough to hold the mixture so that it is no deeper than 4 inches and no shallower than 2 inches. Add the sausage-pork mixture and stir well.
Cook on the grill, uncovered, for 3 1/2-hours, or in the oven, covered, for 2 1/2-hours until hot and bubbling and the flavors are well blended.