How to override inference rules

I want to reuse an expression from base language but with an expanded typesystem. In detail the NotExpression should be usable with more types than boolean. So I created a new inference rule with the overrides attribute set to true. While error messages from the new rule are shown, the equatations of the original rule are still used. I do not really understand the meaning of the attribute.

Is there any way to disable inference rules in an imported language?