Child doesn’t have the father last name

From a procedural standpoint, if a guy comes forward and claims that he is the child's biological father, he can file an application with the court to establish paternity and seek parenting time and or primary custody of the child ( under proper circumstances). Obviously, if he is the biological father, he will also have to pay child support for the child as well. If he currently is supporting the child but does not know that he is the biological father, at some point in the future, if he wants to file an application seeking to establish paternity, he can do so as well.