Board Thread:Naruto Discussions/@comment-24898250-20140730025315/@comment-24519434-20140802215528

ItachiWasAHero wrote: I never said Itachi's MS, I said he could take the the MS eye of Shisui out of Itachi's's crow and switch it with the eye he got from Obito, just maybe Kakashi may get an EMS, therefore the strain would be damn near gone, he would have Kotoamatsukami AND Kamui but yeah it didn't happen

Shisui and Obito being related is not proven everyone just kinda guessed on that, but Kakashi could have put both of Obito's eyes in the same socket to get EMS.