What is the ruling regarding the legal basis for the grandmother's fixed share when she is also a sister?
Chapter on Distant Kindred (Dhawu al-Arham)
Al-Mughni
Book of Inheritance Shares (Farā'id)
Primary text
Those who prioritize the stronger relationship (grandmother over sister) grant the grandmother an inheritance share, even though the basis for her fixed share is disputed, with some holding it is merely a gratuitous gift (*tum'ah*) and not a divinely mandated fixed share (*fard*). If they grant her inheritance based on being a grandmother while the son supersedes the sister relationship, they must consistently grant her inheritance based on being a sister, as the mother supersedes the grandmother.
Supporting text
If they argue that the sister relationship is stronger because the sister's potential inheritance share is larger, this leads to a contradiction in the case of a mother who is also a sister, where they must then argue the mother relationship is stronger than the sister relationship in that specific scenario, thus making the stronger relationship inconsistent.