Need Quick Help in Saving a "Whisked Away" Child! SOLVED!

In another thread I mentioned the strange disappearance of one of my sims. She was apparently "whisked away" even though I wasn't playing her family. Now, I'm playing the family of one of her friends. Deidre was able to invite Kaci over -- and she showed up. In previous versions of the game there was a cheat to add a sim to the family. I did look for "invite to move in" but I think that's a social only for adults and/or romance.

Can someone tell me, please, how to add this little girl to the family I'm playing so I can eventually return her to her own family in Household Management?

EDITED TO ADD: Hallelujah! I found the cheat. After enabling "testingcheats on" I was able to shift-click on little Kaci and add her to the family she was visiting! Her icon however has the "go home" symbol on it. I'm wondering if she would indeed go back to her own family. I'm not going to risk trying it and maybe losing her again, though. I'm just delighted to have brought her back.