There have been so many different ways to do Alternate History that I have seen here on the Wikia, with some keeping certain people, places and ideas the same while others go and change everything to make it as unlike real history as possible. I fall somewhere in the middle between these two extremes, and I want to explain it today, and my made up theory when it comes to the multiverse, and how I use it to explain things.
There are two important things when it comes to Alternate History: how to make it similar yet different from our world, and how to make the changes stand out yet also blend in. It's hard to do this, much less outline a formula to make it clear. That is where keeping people, places and ideas similar to our world is important. A great example would be the Second World War. In many of the timelines I have come across and written, the Second World War - or a parallel to it - always takes place somewhere between 1935 and 1950, usually in the 1940s. It can be a long or short war, but by the end of it, a major change takes place. Most of the time it's that Nazi Germany has managed to take over Europe, if not the world. However, the details within that war seem to face very few changes: often their is a Battle of Stalingrad, or an invasion of Occupied France, with a Charles De Gaulle, George Patton and Erwin Rommel coming to the forefront. This is true even if the POD for the Alternate History takes place decades, if not centuries before. When I wrote French Trafalgar, British Waterloo and it's Third Global War, I had many of the same characters pop up: Hitler, de Gaulle, Roosevelt, Rommel.
I'm not a huge believer in the Butterfly Effect: changing the smallest thing, like steping on a butterfly in the Jurassic period will result in massive, nearly catastrophic changes in the future. It does take bigger events, like killing Adolf Hitler in 1938, to cause changes in the history, though the small events in history that lead to bigger events, like the little details that allowed Hitler to escape death in each of his assassination attempts. To simplify this explanation: random small events do not matter, but small events in larger ones do.
I do not see anything wrong with this. In fact, so long as they fit the story I would be comfortable using almost any name that comes up. Just because this is alternate history does not mean that even the smallest details change. In fact, in my multiverse theory that I use when making AH, I say that small details like people and places can be left the same, with only a few being changed (an example would be Regina, Saskatchewan: since in OTL it is named after Queen Victoria, in an ATL where the British do not control Canada, it should be named something else, for example Wascana.) As long as it does not interfere with the giant overarching story, you can leave things like this.
I like to think that some things like love between two people and births and death can be influenced, but not to a huge degree. Sometimes it's easier to just have some people meet and marry and have children like in OTL than to rewrite the history of every single person from a POD to the present. There is not enough time, energy or ability to research thousands, if not millions of people, just to write an Alternate History. This may be a cop out, but I think unless it's a monarchy where marriages matter for prestige and position, wouldn't a person still love the same person no matter the time period? That said, I will change births and deaths by a few months to a few years in either direction, just to mix it up and prove, yes, that this is Alternate History.
So where does the Multiverse theory come in? In my convoluted theory that has no scientific basis whatsoever, and may be more akin to a writer's device, I like to think that the Multiverse is a huge branching tree: each fork is a POD that results in two or more timelines. Now, after that, my multiverse starts acting weird; some multiverses start bleeding onto others, forcing their ideas or culture and/or history onto others. Again using FTBW, I decided to make a Doctor Who, only instead of British, it's American, and starts in a different time period. Also why I have things that we know in my video games article. In my Multiverse, anything that has ever been made or created is actually another Timeline, just "influencing" the creator to make it. This is why, in my theory you have Doctor Who and then Doctor Who in FTBW and Doctor Who in 1983: Doomsday and Doctor Who in A World of Difference. It's the same timeline influencing all the other timelines, including our own.
I hope this explains some of my ideas about how I use OTL events and the multiverse. I plan to use this idea in stories in the future heh.