is it a possibility that kakashi simply with the genius that he isfound a way to copy the MS from itachi when he was attacked with it?

anyway we can guarantee that Rin is dead however the circomstances of her death (this is unless there is some sick Rin plot) are currently unknown to us.

also is it a possibility that itachi instilled the MS in Kakashi?

Why would he do that? Can't find any other reason than Itachi did it for the case that Naruto couldn't beat Sasuke, and then made a backup plan with giving Kakashi the MS. This is possible since Itachi gave Sasuke his MS abilities, but then why is it a whole new kind of MS jutsu Kakashi introduced and not the same as Itachi and Sasuke if it was the scenario that it was given by Itachi? Not saying this is what happened, but we can't say it aren't true. Most unlikely but still..

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How can I ever be Hokage, if I can't even save one friend?
Isn't that right Sasuke?

Maybe another of his friends died during the time-skip. And the built up sadness of Obito, Rin, and his other friend(s) caused MS to form.

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Run... Run, and cling to life.