What is the ruling on claiming the right of a deceased son from his father's inheritance, the father having died after him?

A son who dies before his father has no share in his father's inheritance. Therefore, the grandson has no right to the grandfather's inheritance unless he is the sole heir (i.e., the grandfather had no direct son). If the only heirs are the grandchildren (male and female), then the inheritance is divided among them by ta'sib (agnatic inheritance), with the male receiving the share of two females, in accordance with the Almighty's saying: "Allah instructs you concerning your children: for the male, what is equal to the share of two females" (An-Nisa: 11). Thus, the inheritance is divided into seven shares: one share for the granddaughter, and two shares for each grandson.