Is it a sin to cut off ties of kinship with a sister who has bad morals, supports strangers, raises deviant children, and causes psychological and familial harm?

The Sharia commanded maintaining kinship ties and did not prohibit maintaining ties with a disobedient relative. However, shunning a disobedient relative revolves around what is beneficial: if it helps bring them back to righteousness, then that is preferable. If the best approach is to maintain ties with them while offering advice, then that is preferable. If maintaining ties leads to harm, then it is not obligatory. Kinship ties are maintained through visits, communication, and anything that is customarily considered a connection, and among the greatest ways to maintain it is enjoining them to good and forbidding them from evil. A believer's heart should be expansive with mercy for the disobedient, and they should hope for their guidance.