Inheritance division when there are multiple sets of sisters with differing parentage (both parents, father only, mother only).
Chapter on Distant Kindred (Dhawu al-Arham)
Al-Mughni
Book of Inheritance Shares (Farā'id)
Primary text
The wealth is divided such that three-fifths goes to the offspring from both parents. The father's sister receives one-fifth, and the mother's sister receives one-fifth. This is based on them taking the place of their mothers.
Supporting text
The same ruling applies if there are three separate paternal aunts (عمات) or maternal aunts (خالات). The doctrine of Ahmad and the rest of Al-Manzileen concerning the offspring of sisters is that the wealth is divided among the sisters according to their respective shares, and whatever reaches each sister goes to her offspring. If there are three separate paternal aunts, their inheritance is distributed among them as the inheritance of separate sisters from their brother. The same rule applies to three separate maternal aunts because they are sisters of the mother.