Even if you were able to find a way to do such a thing (which I don't think you're going to be able to do), that would just confuse your users. I would strongly advise against it.

Instance parameters are controlled from the "quick" properties palette while the type are controlled from the "Edit Type" Dialog box. If the users you are working with understand the differences between a type parameter and a instance one, they will know which change implies which aftermath.

Modifying a type parameter from the quick properties palette (just like modifying it as it was a instance parameter) would probably make believe the user they change it as they want... without having to duplicate the types before doing so. You don't want that.

Could we know what that question was intended for? We could try to find another solution.