Board Thread:Theories and Speculation/@comment-34661853-20181111160651/@comment-34661853-20181121004238

I thought here, when madara implanted hashirama's cells, the cells had effect on the madara's body and he gained the powers of hashirama (mokuton) and of rikudo (rinnegan). If it were to the contrary, if hashirama had implanted the madara's cells, hashirama would have gained the powers of madara (sharingan) and of rikudo (rinnegan). So, the fact is that in relation to the rinnegan obtained by the transmigrans, they must always have the sharingan and the rinnegan, not because one depends on the other, but because one of the transmigrants has that power. If Indra's transmigrant awakens the rinnegan, he already has the sharingan, and if the Ashura's transmigrant wakes up rinnegan, he had to pick up cells from the indra's transmigrant and gain his power in the same way, so they will always have the two doujutsus.

Obviously without considering cellular modifications.