Of course, the first question that would most likely come to people's minds is - would Marty Jr even name his son Marty III? In my fic universe, I just figured - why not?

Okay, here's what I'm thinking about.

In all of my universes, except for possibly Twin Pines Universe, Marty McFly Sr has Marty McFly Jr - then Marty McFly Jr has Marty McFly III. However, in the Trilogy and Haven Universe, Marty Jr marries Harmony Brown - while, in all the other universes, Marty Jr marries Stephanie Stebbs.

Here are a few traits I'm thinking of giving him:

1. He looks identical to his father and grandfather, and Michael J Fox.
2. Instead of becoming a musician like his father and grandfather, he becomes an actor.
3. He is ofen referred to as "the new Michael J Fox" - which amuses him some of the time, and frustrates him at other times.
4. He played Tiny Tim in a modern (futuristic, to us) adaption of The Christmas Carol in 2045, which parallels how Michael is slated to play Tiny Tim in an animated adaption this year.
5. In early 2047, he co-stars with Michael J Fox himself - as his grandson!

It would seem kind of redundant but then again, there's three generations of Goldie Wilsons. Marty named both his son and daughter after him. In the animated series, Biff's son is called Biff Jr, but I think that's sort of overkill. I think there's about a 50% chance that Marty Jr would name his son Marty III.

Well, I don't completely disagree with you. I can see both sides to this.

Actually, I was thinking think a little about the Goldie Wilsons. Goldie Jr follows in his father's footsteps, and becomes the Hill Valley Mayor, while Goldie III takes a different career path. So I thought it'd be neat to do the same thing with the Martys. Marty Jr becomes a musician, like his father - but Marty III takes a different career. I suppose Michael Jandrew McFly could work, too - but that's what Calvin names one of his twin sons in the Almanac Universe (Alexander Patrick McFly is the other one).

Don't get me wrong, I think Marty III could work. If Marty names his son Marty Jr, of course he'll be expected to name his son after him.

I wonder if Goldie III names his son after him.

Well, in my fic, I had Goldie Wilson III break the tradition - and name him Caleb. The same will probably be true of Marty McFly III, if I ever get far ahead of time in my fics.

Right now, I'm kind of looking at having Marty McFly III being pretty much the same person in all the universes - even if his mother is Harmony Brown in two of them, and Stephanie Stebbs in the rest. These are actual separate universes, after all - not just separate timelines.