The genealogy of the whole Dir clan is weird to be honest. Having researched the clan system I believe the original clan system of Somalis was not like it is today, and was more akin to the Rendille clan system where there are a mixture of lineages, moeities and confederations, which over time has been streamlined into the modern Somali clan system and moeities and confederacy names have become ancestors in the abtirsi recitation.
This is why subclans of the same clan do not have the same number of fathers, as some subclans are older than others. Dir clans, almost universally, have short lineages. Gadabursi for instance counts about 25 generations to Dir, compared to 40 for Abgaal Hawiye for instance.
I believe that the Dir clan was originally a different tribe that lived to the west of other Somali tribes, and when the Somali kingdom broke up around 1150 and Somalis moved west, Dir people were incorporated into the Somali nation and were added to Irir Samaale, in the same manner that Xarla was added to Daarood later on. Around this time Daarood split from the Sagaalka Samaale to make a stand alone tribe and there are few traces left of their original connection to the Sagaalka Samaale, the new origin story for Daarood incorporates their dominance over Dir and explains it.