just a related comment.
SIKHS and GURMATT doesnt attach an iota of importance to "family/descent/lineage/etc etc etc"
Gurgadhi was passed on on MERIT..to the most qualified.
Guur nanak ji REJECTED BOTH his blood sons...so did Guru Angad Ji..so did Guru Amardass Ji.
From Guur Ramdass ji gurgadhi did pass on among the FAMILY..but the Criterion still remained MERIT...not age/seniority/physical build/etc etc..Eldest Prithi Chand was rejected in favour of Youngest Guru Arjun Ji...elder Ram rai was rejected in favour of 8 year old Guru harkishan ji....
and finally Gurgadhi was passed to GURU GRANTH JI.
Its just a matter of "history" nothing more.
Gyani jarnail Singh