There is a mechanism from a wiki that I think worked well.
If you have a link to a page that exists, the link shows up as blue. But if the link is to a page that doesn't yet exist, it is red. And clicking on a red link brings you to a new blank page where you can fill out information, after which the link will turn blue.
The analogy here is that creating a new user with @name will show up as red if "name" doesn't exist. Click on "name", and it takes you to the character page where you can fill out that character info. Or, don't click on it yet if you are not yet ready to do so.
If I have a link to @name, and I change it to @nombre, and "nombre" doesn't exist, then you are specifying a new name, and you get a red link.
If what you really wanted to do was to rename "name" to "nombre", then go to the "name" character and rename it "nombre", and it will change everywhere it is used.