Yes, if you'd like to customize these sausage turnovers, you can add in different ingredients, either replacing the sausage or adding half sausage and half another ingredient. I would not change the proportions of the cheese and cream cheese, however, since these add moisture to the turnovers and helps "glue" the filling together. When choosing alternate ingredients, I would also avoid overly wet ingredients (such as uncooked vegetables) so the turnovers don't leak and get soggy. Here are a few other filling ideas you may want to try: chopped pepperoni, chopped ham, shredded chicken, olives, or cooked spinach (squeeze out any excess moisture before adding!).