This concept takes place during “cutie re-mark” PT 1 and 2. Anyone is free to use this idea as long as they credit me and Link the work Here.

The main part of the idea comes from Having twilight accidentally, Or purposely, take somepony from one of the alternate timelines back with her to the OG timeline, such as (eternal night Vr) Rainbow Dash, (Changeling Invasion succeeds Vr) Fluttershy, (war against Sombra Vr) pinkie pie

Or other versions like…

(changeling invasion Vr) pinkie pie, (war against Sombra Vr) Rainbow Dash, (eternal night Vr) rarity
Or use One of the main six from one of the timelines we only got to see a few moments of, Like the Tirek or flimflam brothers timeline.
Or, Maybe you could go for something completely different like bringing the villains from those timelines to the OG one.

There can be so many different interpretations of this idea with numerous different paths the story can follow, from humor and adventure, or drama and hurt/comfort, depending on how the writer views what happened in the episodes and where are you want this to go.

7904824 In the novel:

TSweetie Belle Gains a Soul

• MLP: FiM
• Adventure
• Drama
• Slice of Life

In her darkest hour, Sweetie Belle finds salvation, but it comes with a terrible curse.

• Twilight
• Rarity
• Sweetie Belle
• CMCs

Bad Dragon · 132k words  ·  178  45 · 6.7k views

everypony is replaced by a different version of themselves due to the past being meddled with. Their memories are also replaced, so they don't even know that the replacement is happening.

Only Twilight, Spike and Glimmy can see the effects because they were the ones who changed the timeline just by appearing in the past. Everypony has become a darker version of themselves, including the main character of the novel.

7904829
Pretty close, but I am more referring to the idea that they aren’t overwriting the OG, because it takes a lot of interesting possibilities out of the equation.

7904824
Interesting idea. But it would require some work to straighten out, since a character from one of those alternative worlds most logically wouldn't arrive at the present time in the original timeline, but at the past where Starlight and Twilight were still battling it out. Their presence would make it even a bigger mess with the timeline and the situation between Starlight and Twilight. Resolving all of that would be a big headache, unless you just handwave it for the character to somehow sneak through all those dramas and magical shenanigans and end up in the present original timeline Equestria.

Actually, I did mean it as when the battle between twilight and starlight was happening, But I do agree with you on the rest of the points!