How can one maintain kinship ties with a brother who does not stop slandering, insulting, and cursing, refuses to rent out the inherited house, does not visit his sisters, and curses his deceased parents?

A man cursing his parents or one of them is among the gravest of major sins, based on the hadith: "Indeed, among the greatest major sins is for a man to curse his parents!" It was said: "O Messenger of Allah, and how does a man curse his parents?" He said: "He curses a man's father, so he curses his father, and he curses his mother, so he curses his mother." Maintaining kinship ties is an obligation in Islamic law, even if the kin is a disbeliever. Kinship ties remain obligatory even if the other party severs them or treats one badly. Maintaining ties can be achieved through any customary means, such as calling or giving a gift.