The process for adding trade names is different in every state.
In Washington state, it is both easy and cheap. You file a new Master Business Application, pay $15, plus $5 for each new trade name, and in about two weeks, you’ve got your updated business license.
I’d be surprised if it was much more difficult in Wisconsin.
If you are thinking of going multi-state or international, it’s a good idea to look into services that ensure your exclusivity. That way east coast Psycho Originals doesn’t run into the west coast guys and suddenly have a problem.
IIRC, Anita Roddick stole the idea of “The Body Shop” from a San Francisco store doing the same thing, and probably thought when she started in England it would never be a problem. A few million later, when she got to the USA, she had to buy out their rights.
OTOH, a name does not grant exclusivity. Apple computers bumped up against APple Records back when both were big. They came to an amicable settlement - basically, as long as the businesses were different enough, nobody would confuse them for the same company - until Apple Computer started selling iPods too and ended up in the music business - the lawyers got together for a second round of negotiations.
That’s how you could have, for example, West Coast Publishing and West Coast Liquor, to make up an example.
So with registries in 50 states, plus 100 or more countries, plus lots of case law - when you become big enough to worry about it, hire a good law firm.