What is the way to help reconcile and mend ties between a father and his paternal aunt, given the father's refusal to speak with his sister after learning about the incident of the money she split with her sister without his knowledge, and the resulting psychological harm from the annulment of his daughter's engagement to his cousin?

The matter is too trivial to lead to the severing of kinship ties. The paternal aunt returned the money, and her responsibility was cleared by its return. The breaking of an engagement is not necessarily an injustice. You must maintain ties with your relatives, and it is impermissible for you or your father to cut ties with your aunt. Maintaining kinship ties is achieved through whatever is customarily considered a connection, such as financial assistance, fulfilling needs, visiting, and corresponding. Strive diligently to maintain ties with your aunt and all your relatives righteously. Speak with your father, explaining the obligation of maintaining ties and the prohibition of severing them, and strive to reconcile them, for there is a great reward in it. The Messenger of Allah, peace and blessings be upon him, said: "Shall I not tell you of something better than the degree of fasting, prayer, and charity?" They said: "Yes, O Messenger of Allah." He said: "Reconciling disputes among people, for discord among people is the razor."