For what it's worth, I agree with all who say "do whatever you want in fiction." It is fiction and nobody should take it as reality. historical or not. I am working on a non-fiction book right now and what do you know, all sorts of things that are taken as fact today turn out to be pure fiction, so I have to provide source documentation (that will be ignored, I am positive).

Different related problem, I wrote a four book series set in the 2030s. Two people who worked with me on it wrote sequential fanfic stories on a similar timeline. I wrote a new story with an "alternate future" beginning at the same point in the 2030s as the original. Now, I have a hard time explaining that "alternate future" means nothing more than same characters, same setting, different events. Even with stories that are pure fiction, readers want to argue with you about details that you made up all by yourself.