evidence. The principle you mentioned is correct when the person connected through an intermediary takes that intermediary’s place in the latter’s absence. Thus, the rule is that whoever is connected through an intermediary is excluded by that intermediary, provided that he would take the intermediary’s place in the latter’s absence. The paternal grandfather and the paternal grandmother are equal in this respect: when the father is present, his mother inherits, whereas his father does not—glory be to Allah—because the father’s mother does not take his place when he is absent; rather, his father—the grandfather—takes his place. Therefore, the father excludes the grandfather but does not exclude the grandmother.
Thus, the rule—which many scholars state without qualification—that whoever is connected through an intermediary is excluded by that intermediary, except for maternal siblings, must be qualified: whoever is connected through an intermediary and takes that intermediary’s place in the latter’s absence is excluded by it; whoever does not, is not. Accordingly, the father’s mother inherits alongside the father, and the grandfather’s mother inherits alongside the grandfather. If a deceased person leaves behind his father and his father’s mother, the father’s mother receives one-sixth, while his father receives the remainder, since he inherits as a residuary in the absence of a descendant heir. Here, then, the mother inherits alongside the father, although she is connected through him, because she does not take his place in his absence.
His statement, “just as [she inherits] alongside the paternal uncle,” means: just as she inherits alongside the paternal uncle by consensus, even though the grandmother—the father’s mother—is also the paternal uncle’s mother. It may therefore be said: if she inherits alongside her son, who is the paternal uncle, then how can she not inherit alongside her son, who is the father? There is no difference.
His statement, “A grandmother related through two lines inherits two-thirds of the one-sixth,” means that the other grandmother receives one-third of the one-sixth. Thus, if two grandmothers are together, one of whom is related through two lines and the other through one line, the one related through two lines receives two-thirds of the one-sixth, and the other receives one-third of the one-sixth.