The ruling on inheriting from a father who died before his grandfather

Question:
Honorable Shaykh, this questioner says: We have a custom where if a man marries and has children, and then dies while his father is still alive, the custom is that if he has children, when the grandfather dies, these children share their father’s portion with their uncles. For example, if their father was Hakim, is this practice permissible in the Shari'ah by creating heirs or by the testimony of two just men?

Answer:
If the deceased’s share is one-third or less, there is no harm, because a person may bequeath one-third of his wealth to a non-heir, and these children are not heirs in the presence of their uncles, so it is permissible for them in that case, or less than one-third. However, if it is more than one-third, it is not permissible except with the permission of the heirs after the death. If they permit it, it is valid; otherwise, the right belongs to them to take what exceeds the one-third. Yes.