Chapter on Residuary Heirs
Know that every female heir receives a fixed share; none of them is a residuary heir in her own right except the emancipatrix.

All male heirs, by contrast, are residuary heirs in their own right, with the sole exceptions of the husband and the uterine half-brother. Sisters, however, become residuary heirs when daughters are present; and the daughter, the son’s daughter, the full sister, and the paternal sister—each of these, when accompanied by her brother, becomes a residuary heir through him, the male receiving twice2 the share of the female.

The rule governing a residuary heir is that he takes whatever remains after the fixed shares have been distributed; if nothing remains, he receives nothing. If he is the only heir, he takes3 the entire estate. The grandfather and the father, however, have three distinct situations: (1) they inherit as residuary heirs only when there is no inheriting descendant; (2) they inherit by fixed share only when the descendant is male; and (3) they inherit by both fixed share and residuality when the descendant is female.

Our regular principles do not apply to the so-called mushtaraka (joint case), which consists of: the husband, the mother, the uterine siblings, and the full siblings.