What is the ruling of Islamic law regarding the inheritance of sons who passed away during their father's lifetime, from their grandfather?

Grandchildren (sons and daughters of the son) do not inherit from their grandfather when their paternal uncle is present, because the son, by consensus, blocks the son's son and the son's daughters from inheritance. Similarly, their father, who passed away before their grandfather, would not inherit from him. It is recommended for their paternal uncles and the grandfather's heirs to give them something from the inheritance to comfort their hearts, especially if they are in need, in accordance with the noble verse: "And when [other] relatives and orphans and the needy are present at the division [of inheritance], then give them [something] from it and speak to them words of appropriate kindness" (An-Nisa: 9).