When encoding, go into the subtitles section, select english from the list and then tick all three boxes next to it "Forced Only", "Burned Inn" and "Default". This will burn subtitles for foreign audio into your movie.
If there is more than one subtitles track for english, you will have to watch the DVD in a player like VLC and find out which of them is the one you want, although, they will probably all work.
I do this for every movie I encode. If there isn't any foreign audio in the movie, nothing happens, if there is, I get subtitles. I often encode films that I havn't seen yet, so this extra security is nice to have.