Fewer subtitles than videos

[mopihu]

I can't seem to figure out how to deal with a situation where you have fewer subtitles than video files. I'm trying to mux a season where there's foreign speech, but only in a few episodes. I have forced subtitles that covers only the foreign speech, but when I add them to the subtitles tab, they go to the top of the list, and cannot be moved down to the episodes they belong to. Is this not possible to do or am I missing something here? Thanks!