Or it’s Mirror Mirror Murphy, or it’s her ghost, or it’s Murphy from the past, or she comes back as an Einenjharen prematurely.
My favourite is a variation on the one and four, future Einenjharen Murphy travels back in time from a period where she is lost to mortal memory, because she is travelling back from a future universe where Harry (and all other mortals ) have died young in the BAT. Her role? To aid in a decision by Harry in which he wins the BAT creating a universe where humanity survives and wins. She cheats the whole mortal memory thing by being a Murphy from a parallel universe settling down in other than her original universe. Both Harry and Murphy have to deal with having recently seen the other dead, Harry giving up his life to set up the magic sending her back (Soulfire) and the first thing she see as an Einenjharen in the mortal world is Harry’s fresh corpse. She’s Odin’s backstop.
Basically Jim rips off Harlan Ellison (hey it’s happened before!, and you only steal from the great).
You can’t have too many conspiracy theories piled on top of each other, and this fits all known WOJ on the subject, Murphy returns, mortal memory, and Harry breaking all the Seven Laws.
And it will just piss off a certain segment of the fandom, which is why Jim will do it. You know who you are.
If we are going down this route, the the Malcolm who visited Harry was a Malcolm from literally just before died, given a chance to see Harry grown up by Uriel and the Angel of death, to nudge Harry back on the right path.