Swiss German vs. the other two main variants

Today I ran into a problem that I don’t know how to solve: I wanted to write a rule that can distinguish between Füßen (German for feet) and Füssen (name of a town in Bavaria), and one that prohibits the spelling Meissener, which is (for Germans and Austrians) almost always wrong. But this does not apply to Swiss users.
Is there a way to disable these rules when the language is set to de-CH? Strangely, I have never encountered the problem before.

If a variant should disable some rules of its super language it can be done like this: languagetool/ValencianCatalan.java at master · languagetool-org/languagetool · GitHub

Ah, thanks.