What is the ruling when a mother is present with two brothers, or a brother and two sisters, or four sisters and a grandfather?

Primary text

When a mother is present with two brothers, or a brother and two sisters, or four sisters and a grandfather, the distribution of the remainder (thuluth al-baqi) and partition (muqasama) are equal. If they exceed this grouping, the grandfather receives one-third of the remainder, and the problem resolves into eighteen parts: the mother receives three, the grandfather receives five, leaving ten parts for the brothers and sisters, which is then distributed among them proportionally. If the brothers and sisters are from both sets of parents (paternal and maternal), the entire remainder goes to the children of both parents, unless the child of both parents is a single sister, in which case she receives her prescribed share, and the rest goes to the others.