Do grandchildren inherit from their deceased grandfather or grandmother if their father passed away before them, or do the grandfather’s brother or the grandchildren’s mother inherit from them?

If the grandfather passes away and has no direct son, then the grandson and granddaughter inherit from him, and the brother does not inherit if there is a grandson. If the grandmother passes away and leaves no direct son, then her grandchildren (grandson and granddaughter) inherit from her. However, if the grandmother is the mother of the grandfather, and the grandfather's brother is her son, then he inherits from her and disinherits her grandchildren. It is forbidden to ask about matters that have not yet occurred.