My solution would be something akin to what happened with Wanda but a little different.
Mephisto wanted to "feast on" Mary Jane and Peter's happiness when he made the deal right?
Have that happiness manifest itself into a person. That person being Mayday, the child that Mary Jane and Peter would have had.
Make her a teenager or what have you, maybe even start her off as evil/working for some evil entity(probably Mephisto or an underling so that Mephisto has plausible deniability for the time being)
And have it be a mystery who this new "spider-person" was causing all this trouble.
Have it eventually revealed, that it's Mayday, the child Peter and Mary Jane would have had, but essentially gave up in order to save Aunt May's life.
Have that part of the story given to Mayday and shaped her growth which is why she holds disdain for Peter, Mary Jane, Aunt May, etc.
Give her an arc where she eventually becomes her own version of a hero, and create something of a barrier with her and Peter that they'll eventually work through years later when they finally embrace as father and daughter. But also having it create something of a tension between her and Mephisto.
Which eventually leads to the potential prophecy happening, but it gets more layers when you realize Mephisto had used the happiness he took from MJ and Peter in order to create Mayday in the first place as
she WOULD have been their
happiness.
Giving this scene full context but also an element of personal vendetta, and
their story(Mayday and Mephisto's) needing to reach it's conclusive showdown.
That's how I'd do it anyway.
It also doesn't compromise any future stories editorial wants to tell.
Mayday exists in the 616 as a teenager(and grows with time). Peter doesn't have to be "married". Peter and MJ's relationship can be anything the writers at the time want to play around with, because Mayday already exists. And Mayday exists initially as an antagonist as a final consequence to OMD being that she's what they unknowingly gave up when they sacrificed their marriage, and Mephisto feeds off of that for one final cruel joke. But also in his arrogance, unwittingly creating the person that ultimately leads to his defeat at some point in the future.