How can a woman grant or bequeath her land and house to her sister during her lifetime or after her death, while observing the rulings of Islamic Sharia, and with the condition of retrieving the grant in the event of childbirth?

A person is permitted to dispose of their property through a gift (hiba) or charity (sadaqah) if the disposition is immediate. However, if it is contingent upon the death of the donor, it takes the ruling of a will (wasiyyah). It is not permissible for a gift to be made to an heir unless the adult, mature heirs approve of it, and it must not exceed one-third (of the estate). It is not permissible to use deception to deprive heirs of their right. Rather, it is advised to be patient, supplicate, and show kindness to those who have wronged you, based on the saying of the Prophet, peace and blessings be upon him: "Connect with whoever cuts you off, give to whoever deprives you, and turn away from whoever wrongs you."