It didn't work. I tried JFK-AMS and it showed only NW flight. Same thing for DTW-AMS. For DTW-VCE, it said there's no flight. I used Rulebuster option on October 3rd.

The system should be more intelligent. It won't show any availability in First if there's at least one segment not having FC cabin. Same thing for BC. So if you want to book a BC ticket from the website, you must leave from a gateway only, I guess.