ولو أوصى لبني فلان، وله بنون وبنو بنين كانت الوصية لبنيه دون بني بنيه
If a bequest is made to a person's sons, and he has both sons and sons' sons, the wording refers to the sons rather than the grandsons.
The direct referents of banun are sons. Including grandsons by an extended sense raises the problem of joining literal and figurative referents in one expression. In this stated interpretation, the bequest is confined to the immediate sons.
Entitlement under a testament therefore turns on the wording and its interpretive principles, not merely on family connection. A differently worded testament or a separate contextual indication could yield another case.