Best route for has_many subrecords

Hello all,
I have a model, say it’s called Person, which has_many Responsibilities. I would like the “show” view for the person controller to list all of the responsibilities for that person. (That’s the easy part – I think I know how to do that part.) At the end of the list, I would like to include a text field into which a new responsibility may be added. What route should I use for the “Add” button next to that text box?

I am, perhaps, confused, because I’m using RESTful routing, and I can’t figure out how to map this sort of action (add/update one of the subrecords of a has_many association) into a RESTful route. Perhaps wanting to do this sort of thing from the “show” view is not compatible with RESTful routing.

I suppose I could create a controller just for the Responsibilities model, and I could nest the routes for that inside the routes for the Person routes, but that seems like overkill, especially since I only need to be able to create and edit responsibilities.

Or is it? Is that the “Rails Way” to do this sort of thing?