That's roughly the same approach I've taken as well. I currently have one group for the parent tag and a separate group for the subtags, resulting in a 1:3 relationship.
In the parent tag, I've added an extensive description explaining the function and context. Each subtag includes a similar description with an explicit reference back to the parent tag (e.g., "This subtag belongs to the parent tag '[name]' and represents score 100%").
Not perfect indeed, but it works for now. Definitely hoping for true parent–child tag hierarchy soon! 🤞