דברי הימים א, פרק ח׳, פסוק י״ח

Tracing the family lines of ancient Israel often reveals careful distinctions between different generations. In the ongoing family records, Ishmerai, Jizliah, and Jobab are grouped together as descendants of Elpaal. Elpaal is a figure who was already mentioned earlier in the family tree along with several of his children [ביאור שטיינזלץ].

Because these three individuals are recorded separately and were not included in that earlier list of children, a clear distinction is being made. It is understood that these men are not Elpaal's direct children, but rather his grandsons. This generational gap is the reason they are kept apart and not counted alongside his actual sons [מצודת דוד].