What is the ruling on transmitting speech related to honor to verify its authenticity, and to set limits for the person spoken about if it is true, or for the one who spoke the words if they are false, in order to avert corruption and discord? And what is the ruling on cutting ties of kinship with someone who was the cause of this, or not maintaining ties with the sons and daughters of brothers and sisters? And is the one who does so considered sinful?

It is not permissible to transmit كلام (speech/words) between people in a way that leads to discord among them, unless a legitimate benefit is hoped for. The core of the problem here is the niece's actions. Wisdom should have been exercised in handling the matter and informing someone who could rectify her behavior to avoid the severance of ties among family members, which Satan loves and strives for. Estrangement is forbidden except for a legitimate purpose, and its prohibition is even greater among relatives because it constitutes cutting off kinship ties. It is advised to fear Allah and strive for reconciliation, and the best of those estranged is he who initiates the greeting of peace. Wise individuals should be appointed to mend the rift. Family ties must be maintained and they should be treated with kindness, even if they cut off relations or mistreat, for Allah Almighty says: "And not equal are the good deed and the bad. Repel [evil] by that which is better; then, suddenly, he to whom between you and him is enmity [will become] as though he was a devoted friend. But none is granted it except those who are patient, and none is granted it except one having a great portion [of good]." And it is obligatory to treat relatives with kindness even if they cut off ties and mistreat. The default for a Muslim is blamelessness, so it is not permissible to falsely accuse him, and the accusation of adultery is slander, which is one of the gravest sins.