Is it permissible for my mother to stipulate in her will that her disobedient nephews be deprived of her inheritance, and that their share be given to her other nephews, knowing that she wishes to give her surviving brother one-third of her money and possessions if she dies before him?

There is no need to concern oneself with how the estates of the mother and maternal uncle will be divided while they are still alive, as this is preoccupation with something that has not yet occurred. The children of the sister are not heirs, whereas the children of the full brother or paternal half-brother inherit from their paternal aunt. Disobedience to parents ( 'Uquq) and severance of kinship ties (Qati'ah) do not prevent inheritance, just as filial piety (Birr) is not a cause for it. Rather, kinship is the cause of inheritance. Impediments to inheritance are slavery, homicide, and difference of religion. Disobedience to parents is a major sin, and its burden is on the disobedient child, but Islamic law has not made it an impediment to inheritance. Employing stratagems to prevent some heirs from inheriting is not among the ethics of believers.