Overriding a single metadata item

I’ve been able to fix a lot of issues I had with Infuse by overriding metadata using tinymediamanager. But now I’m wondering if I have to override ALL of the metadata in order to fix one tag. Basically I have a lot of media that is unrated and for parental control purposes I would like to assign them appropriate ratings. It would be great if I could just have a .nfo file with the proper xml stating the rating that I want it to have and that one tag would be overridden while the rest are left alone. I tried it, but it doesn’t seem to work that way. Is there a way to do this easily?

Currently, metadata overriding via NFO will be all-or-nothing thing. This means you can use an NFO file to remove some metadata items you don’t want to see, but you won’t be able to override only one item and keep the remaining TMDB info.