...wow, talk about a facepalm. That isn't what you were trying to say. You were saying that the Uzumaki were a splinter clan of the Senju, which isn't the case. That would mean that the Senju were already established and the Uzumaki broke away. In reality they were formed separately. One descendant of the younger son starting the Senju, another the Uzumaki. When kishi was saying that Nagato has Senju lineage, after already confirming he was Uzumaki, he wasn't saying that because he was Uzumaki he had Senju heritage. He was saying that somewhere in his lineage an Uzumaki and Senju got together.