What is the legal ruling regarding one of the grandchildren objecting to the division of his grandmother's inheritance, which took place more than thirty years ago, despite his satisfaction with it at the time of the division, especially now that the value of his siblings' properties has become higher than his?

If the grandmother gifted real estate to her adult, mature children, and they accepted it, and each of them took possession of their gift, then this is a binding gift that transfers the real estate from the grandmother's ownership to the ownership of the donee. It cannot be claimed after her death as part of the inheritance.

However, if one of the children was not an adult or mature at the time of the gift, or if there was injustice and favoritism in the gift, then the gifts must be returned to the inheritance and divided according to Islamic law. The proof for this is that the Prophet (peace be upon him) forbade injustice in favoritism and ordered its rectification. If the giver dies before rectifying it, then it is incumbent upon the one who was favored to act justly among their siblings, and they should divide all the wealth according to the Book of Allah.