Is it permissible to dispose of the mother's estate and give living children their shares during her lifetime, with one of the children receiving an increased share and taking the share of his deceased brother through a fictitious sale contract? And does this unjust contract invalidate the obligatory bequest due to the children of the deceased son?

The son who dies before his mother does not inherit from her, nor do his children inherit from her if the deceased has a living direct son, unless the mother bequeaths to the children of her son who died before her a bequest not exceeding one-third. The mother is permitted to give her children whatever she wishes during her lifetime, provided there is justice among them, and this is called a gift, not an inheritance. It is not permissible to compel the mother to give a gift or to sell, and if this occurs, the sale or gift is void, and whoever does so is disobedient to his mother and must repent and return what he took.