There is one other possibility. The other possibility is that all that worrying IS happening, but off camera. As a conservation of detail thing. Or perhaps a deliberate obfuscation for the audience.
I'm not saying that's good writing, but it's entirely possible we will just get some kinda flashback montage in the last movie when we actually FIND the 02 kids where it shows that the original 8 have been quietly worrying about them but then just not having enough information to DO anything about their friends' disappearances.
That's awful writing due to complete lack of proper foreshadowing/development. But it would make me hate the writers a lot less. I think.