Do the children whose father has passed away inherit from their living grandparents? What is the legally and religiously prescribed division for the grandparents' inheritance in this case? And does the son's widow inherit from her husband's parents?

If the grandparents passed away before their son, then their direct children (your paternal uncles and aunts) inherit the estate, with the male receiving twice the share of the female. There is nothing for the children of the deceased son or his wife, due to the presence of the direct children. It is recommended for the deceased to make a will in favor of non-inheriting relatives (such as grandchildren and the wife of the deceased son). If the grandparents did not make a will, then it is recommended for the heirs to give them something from the estate during distribution. It is not permissible to act according to man-made laws that contradict Islamic law. The matter of inheritances is serious and must be referred to the Sharia courts for investigation and to ensure the rights of all. Therefore, the estate should not be divided without consulting the Sharia courts.