This is still real hard for me. Mostly it's out of my control. Sometimes if I want to help a certain part and I know something they like to do or I know something to do which they'd usually be around for, I could do that thing and try to look around inside for them. If say the adult part you talk about comes around when you're at work, you could leave a note at work asking it what you want to know. Or you could try to spend some time with it during your lunch break or something. Or if it comes out during a certain feeling, you could try to recreate that feeling. I find I can't usually do this sort of stuff until I know the part pretty well and we have a connection. Usually I don't have any control over who's around.