Is it Islamically permissible for a son to leave his father's gathering when he smokes, to inwardly disapprove when unable to stop him from smoking, and to carry a bag containing cigarettes for his father?

It is not permissible to sit with a smoker while he is smoking. It is not permissible to carry a bag containing cigarettes if you are aware of it, because carrying tobacco is forbidden and is considered aiding in sin. Apologize to your father politely and inform him that you are ready to help him in everything as long as it does not involve disobedience [to God].