There's a walkthrough
here.
After you're told to locate the others, you need to find two people you haven't met yet, then return to the lounge (the room with the sofa and painting).
The first person should be pretty simple to find. Just make sure you explore every corner of every screen.
You can only find the second person after you've found the first one (this is a pretty big design flaw, by the way. An obvious opportunity for parallelism has been turned into an awkward, arbitrary restriction). So you might have to go over every screen again, and try things that didn't work before another time.
Spoiler:The second person, Jim, is up in the tree outside in the back yard. Push the tree, and then talk to it.
