I think this is really the wrong solution to the problem. I think the real solution would be to make it easier for you to enter a custom dynamic so that you don’t have to use a similar-looking paragraph style. I don’t consider the current behaviour of the dynamics popover absolutely set in stone: the problem is that something like “(non dim.)” is really not a dynamic, in as much as it is communicating the exact opposite thing to a dynamic.
The whole idea behind using semantic objects for things like dynamics and tempos is to avoid having to have bits of text lurking around that look like they are the same, but they’re not, yet the semantics of music are sufficiently messy that trying to design a framework to accommodate all of the things musicians write in their scores is no small task in itself.