In riwāyat al-akābir ʿan al-aṣāghir, an older or more senior narrator transmits from someone junior by age, earlier participation in learning, or scholarly standing. A senior teacher may narrate from a pupil; a Companion may, in certain cases, obtain a report through a Successor.
Parents narrating from children and children from parents are identifiable family patterns. Family connection itself neither establishes hearing nor grades a report.
“ʿAN ABĪHI ʿAN JADDIHI”
“From his father, from his grandfather.”
The referent of the pronoun in “his grandfather” requires identification of the particular family chain. It may not refer to the same generation in every context. Genealogies, narrator biographies and other routes help establish whose grandfather is meant.