Board Thread:Naruto Discussions/@comment-36755597-20180829215104/@comment-1872728-20180906181000

I mean, if Kekkei Tota is the combination of two Kekkei Genkais, then theoretically a Kekkei Tota Sharingan could exist, but it wouldn't be a Sharingan anymore. Assuming that you can only mix two kekkei Genkais of the same category together (elemental w/ elemental, dojutsu w/ dojutsu etc.), you can only mix another dojutsu with the Sharingan.

The only known case of mixing dojutsus is Sasuke, assuming that he mixed his Sharingan with his Rinnegan and not just a weird version of the Rinnegan. His Tomoe Rinnegan is not stated to be a Kekkei Tota, which could mean a couple of things: 1. It should be a Kekkei Tota but Kishi made a mistake 2. Tomoe Rinnegan is not a merger of the Sharingan and Rinnegan 3. There is no non-elemental Kekkei Tota 4. Kekkei Tota is not a merger of two Kekkei Genkais.

As for copying Kekkei Genkais, I don't think that's possible. Unless you are genetically built to be able to do it, nothing in the world can make you just copy a genetically exclusive thing and do it.