What is the ruling on a father making gift certificates for his children (with the male receiving the equivalent of two females' shares), which are not to be disbursed until after his death, with the aim of disinheriting his second wife, knowing that she took enormous sums of money from him and denied it, and that he lives off the profits of these certificates? And what are the Sharia violations in this action and how can they be remedied?

It is permissible for a person to donate whatever they wish from their wealth during their lifetime, provided that they do not intend to disinherit an heir. If such an intention exists, the donation is forbidden and invalid. A donation contingent upon death is considered a will, and a will made to an heir is forbidden and does not take effect unless the remaining heirs approve, due to the Prophet's (peace be upon him) saying: "Indeed, Allah has given every rightful person their due right, so there is no will for an heir." Investment certificates issued by usurious banks are forbidden because they are usurious loans. Therefore, the father is advised to rectify his intention and revoke this donation and return these certificates if they are usurious.