The name "Nyota" had been kicked around for decades in non-canon material. I when the 6th movie came out, there was a magazine about the movie. There were a few pages about each character. But they had her identified as "Commander Nyota Uhura".

My personal fan theory: George KNEW Marty was "Calvin". He was able to convince Lorraine (somehow). They confronted Doc. He spilled the beans. That's why they bought that Toyota pickup & had it ready for him on that particular date. It was a thank you gift.

There's a scene in the episode after "Family" (called "Brothers"), where, at the end, Data helps two young brothers aboard reconcile. Dr. Crusher says something to effect that brothers forgive. Picard is also present, and he gets this wistful look on his face, as if he's recalling his recent reconciliation with his own brother.

That Marty McFly (with all the life experience he had growing up in an entirely different McFly household) made different decisions upon his arrival on November 5, 1955, creating a THIRD timeline.