Is it permissible for me to suggest to my grandmother that she change her will regarding the endowment of her house for the needy among her children, and stipulating a sacrifice (udhiyah) for her, and leaving the house to the heirs, due to my fear that my uncle might wrong his siblings, and because my father has endowed a building, a portion of whose revenue is designated for sacrifices for him and his parents? And would I be disobedient to my father if this change occurs?

If what the grandmother did was a will for the house to be executed after her death, then there is no harm in advising her to change the will and retract it, because it is permissible for the testator to retract or amend their will. This is not considered disobedience, because a waqf (endowment) conditioned on death is considered a will.

If conditioning a waqf on death is permissible (which is the prevailing fatwa), the grandmother can bequeath one-third of her wealth as an ongoing charity, for example, by bequeathing the house if its value is equal to or less than one-third of her wealth, and its proceeds are spent on the poor or orphans, or used for sacrifices.

She is not allowed to make a will for the heirs with a waqf or anything else, according to the preponderant opinion. However, if the waqf was executed during her lifetime, she cannot retract it, and those she designated will benefit from it, and the beneficiaries of the waqf cannot be changed except with their consent.