Change Category sperator (in post editor) from comma

Hi, I am working on a website that has a number of entries that fall into a number of categories. The category names are the names of people which need to have a comma to separate the first and last name.

So for example one category would be “smith, john”. I can add these in “posts > categories”. The issue is that it is much more efficient to add the categories when I am making the post (This way I don’t have to make the category, then find it in the massive list when creating the post).

I know you can add multiple categories in the post editor by separating them with commas, but I need to have commas in the actual name. Is there perhaps a function I can create whereby if I have for example:

“smith–john” it would convert the “–” into a comma?

Thanks in advanced.