Do the strange actions practiced by the parents, such as unusual slaughtering, throwing chickens into abandoned houses, lighting fires to make and burn a paper doll, the father’s extreme nervousness, his constant suspicion that his children will leave or kill him, his aversion to helping anyone, and his possession of the book "Al-Rahma fi Al-Tibb wa Al-Hikma" attributed to Al-Suyuti, in addition to his past disregard for what is lawful and unlawful, have any connection to magic or jinn, and are they sorcerers? If so, how can they be dealt with?

It is not permissible to accuse a Muslim of sorcery, charlatanism, or dealing with jinn without clear proof, so how much more so if the accusation is directed at one's parents? What you have mentioned of matters that engender doubt and suspicion is not sufficient to accuse them of sorcery or association with jinn. The proper way to deal with this is to teach your parents the fundamentals of sound creed, warn them of the danger of sorcery and charlatanism, and disapprove of any innovations or transgressions that appear from them in the best manner, while not falling short in honoring them and being kind to them.