What is the ruling on shunning a father and siblings due to the father's favoritism of one of his children in worldly gifts?

A father's preference for one of his children over others without a legitimate reason for such preference is an act of injustice (ظلم) prohibited by Islamic law. However, this injustice does not permit boycotting him or neglecting to honor him. Rather, he should be advised gently or by seeking the help of someone whose advice he accepts. Similarly, boycotting a brother is not permissible, as cutting ties of kinship (قطع الرحم) has been prohibited; instead, these ties must be maintained even if the other party severs them. It is commendable to advise the brother not to accept injustice or assist his father in it. Regarding a father gifting his residential home to his son: if the son was able to demolish and rebuild it, the gift is valid if there was a legitimate reason for it. However, if the son built the house with his own money, the construction is his right. And if the gift was made without a legitimate reason, it must be returned to the father, and the son is entitled to the value of the construction.