All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
If your father gave all his property before his death as a Hibbah (gift) to his sons apart from his daughters and the conditions stipulated by the Sharee‘ah for the gift were met, then we believe that it is an unjust gift and contrary to the justice that Allah, The Exalted, commanded. Allah Says (what means): {Indeed, Allah orders justice and good conduct…} [Quran 16:90]
This gift involves injustice and wrongdoing and is also contrary to the justice enjoined by the Prophet, sallallaahu ‘alayhi wa sallam, when he said to a man who wanted to give a gift to one of his children and deny the others: “Fear Allah, and observe justice among your children.” [Al-Bukhari and Muslim]
In a narration cited by Muslim, the Prophet, sallallaahu ‘alayhi wa sallam, said to the gift-giver: “Then do not ask me to be a witness, for I cannot be a witness to injustice.” Another narration reads that he, sallallaahu ‘alayhi wa sallam, said: “Would you like them to show equal dutifulness towards you?” The man said, “Yes!” Thereupon, the Prophet, sallallaahu ‘alayhi wa sallam, said: “Then do not do that (i.e., do not give a gift to one child apart from the others)!”
Jurists held different opinions on the case when the father passes away before observing fairness in giving gifts to all his children (by taking it back or offering similar gifts to his other children) as to whether an unjust gift is considered valid and binding or must be taken back even after his death. The majority of the jurists held that it is a valid and binding gift, while some of them held that it must be taken back even after the father’s death. The second was the opinion chosen by Shaykhul-Islam Ibn Taymiyyah and we believe that this opinion is closer to justice and fairness.
Our advice for the sons (your brothers) is to fear Allah, The Exalted, and return these unfair gifts to the inheritance to be divided among them along with the rest of the excluded heirs, as this is closer to Taqwa (piety) and saves their father from incurring the displeasure of Allah, The Almighty.
Allah Knows best.