Is it permissible for a father to divide his property among some of his children to the exclusion of others, on account of one of them being disobedient (aqq)? And does the disobedient son forfeit his right to inheritance?

If a father divides his wealth during his lifetime, while in sound health and full mental capacity, and without intending to harm some of his heirs, then there is no sin upon him, provided there is equality among the children. Preferring some over others is not permissible except for a legitimate Shar'i reason. The father must give the son his share and treat him equally with his siblings. It is not permissible to deprive him or diminish his share due to his disobedience. The siblings should advise their brother and remind him of the seriousness of disobedience and breaking ties of kinship, seeking help from Allah through prayer and through those who have influence over him. Among the greatest things that help in reforming him are kindness and good treatment towards him, as Allah Almighty says: "Nor can a good deed and a bad deed be equal. Repel [evil] with that which is better, then verily he, between whom and you was enmity, (will become) as though he were a close friend." It must be noted that a father's division of his wealth is not valid if it is treated as an inheritance. If it is a gift, then its possession must be legally transferred.