Idk.....
What about Madara?
I dont understand your post but let me put this into perspective.
Sage- has rinnegan + juubi
power split EQUALLY between 2 sons:
Elder Son (ES) - has eyes
Younger son - has body
Seeing as the ES got the eyes and powerful chakra, it can be assumed that he possessed a watered-down version of rinnegan (that spiral looking thing). YS got the body and great amounts of chakra. Stamina is not a problem as powerful chakra and amount of chakra equal out, as i said in my post before.
The manga has stated that it is possible for rinnegan to be achieved by "evolving/upgrading" sharingan. Whether Senju DNA is needed is still up for debate.
Using common sense, we can infer that:
If you are a descendent of ES, you need the body, in form on DNA, which is what you are missing from your genes to unlock rinnegan.
If you are a descendent of YS, you need the eyes, which is what you are missing from your genes to unlock rinnegan.
Seeing as Nagato is an Uzumaki which branched from Senju, it can be inferred that he is missing the eyes. Logically, the only way for him to get rinnegan is through implanting eyes, as i stated above why. More proof of this is: