What should I do about my mother who disinherited me and my sisters, and is seeking to deprive us of the remaining inheritance, after she registered a plot of land to my brothers through a power of attorney from my deceased father?

If the registration of the land was a gift (hiba) from the father, then justice must be observed among the children, male and female, and a void gift must be returned. However, if it was a bequest (wasiyya) to an heir, it is not permissible unless approved by the adult, sane heirs, based on the Prophet, peace and blessings be upon him, who said: "Indeed, Allah has given every rightful person his right, and there is no bequest to an heir." If the registration was done without the father's knowledge or permission, or when he was not legally competent to donate, then it is an unlawful usurpation. Depriving an heir of inheritance is forbidden and a major sin. Allah has threatened those who transgress His bounds with humiliating torment. The mother should be advised kindly, and the unlawfulness of withholding inheritance should be explained to her, while continuing to honor and revere her.