What is the ruling of Islamic law concerning the prevention of the son of a deceased son (who died during his father's lifetime) from inheritance, even if he has poor, young children? And is it permissible to give them something against the will of others?

It is permissible for a man to bequeath to the children of his deceased son during his lifetime a portion less than one-third of his estate, even if their paternal uncles disapprove, because a man has the right to dispose of one-third of his wealth after his death. It is commendable for him to bequeath to them an amount equivalent to their father's inheritance, provided it falls within the limit of one-third or less. If he does not do so, they have no right [to anything] unless their paternal uncles agree.