Is the grandfather's action of registering a plot of land in his daughter's name during his lifetime, while depriving his deceased son's children of it, considered religiously questionable, especially since he justified it as achieving fairness among his children and punishing his deceased son's children for their bad manners and estrangement?

The question is ambiguous and contains issues that require clarification due to the lack of clear details regarding the gift and its binding nature, and the reasons for dividing the aforementioned land are not clear. Since the matter has been referred to the Sharia (definition) court, the court is the one to rule on it. What the grandfather did by registering the house and land in his daughter's name is permissible if it was intended to achieve justice among the children, based on the Prophet's (peace be upon him) saying: "Be mindful of Allah and be just among your children." As for what the maternal uncle's wife and her children did by forging and registering the house in their names with an old date before the grandfather's death, this is not permissible; it is consuming people's wealth unjustly. It is advisable to reconcile and avoid dispute. If the conflict persists, there is no harm in referring the matter to the Sharia court. The intention to return rights is not considered a vow, as a vow has specific wordings.