oro knew granny madara.
pretty sure madara gave the rinni eyes to oro and oro did him the favor of implanting it into nagato in return for hashi dna;-)( only reason he was able to make yamato)
i think oro is in the mix one way shape or form....what if and you could laugh and flame idc but what if madara's body is still preserved there hooked up to the gedo mazou and thats where orochimaru is taing sasuke to bring him back to life, or take his rinni, havent you asked your self what tobi did with the other rinni? nagato had two not one, he implanted the other rinni in madara body along with the eye madara already had.
the main reason oro wanted a uchiha body so bad is because madara told him you cant be part of my plan only if you have the same eyes as me will you not become a slave. so oro was like faq that, he purposely made an edo, then kabuto perfected it with futher research and brought him out before tobi can use rinni tensei on him.
i was just ranting but what you think?