Do the remaining children have a right to inheritance before the mother's death, in light of the brother's actions, which included his illicit appropriation of the father's money and shop, and his attempts to forge the villa's documents that the father wrote in the mother's name for her protection?

What a son takes from his father's money during his lifetime or from his estate after his death is not his rightful due, as the money belongs to all heirs. As for the house: if the mother did not take possession of it during the father's lifetime, then the gift is invalid and is considered a will, which cannot be executed without the consent of all heirs. The heirs are entitled to their share of the estate upon the father's death, and the mother's death does not affect this. Disputes are resolved through the Sharia (definition) judiciary or arbitration.