How do you split a family to move some into a new empty house?

I was successful with a family split, although under slightly different circumstances. My Sim married Alice Spencer-Kim and I had him move in with her and her dad and daughter, and moved the ex-husband and his mom out. I wanted those two to be available for the little girl to interact with, so after the split, I went to "families not in world" (or whatever that's called), found them, and moved them into a house. I had to use the freerealestate cheat, because they didn't have enough money to move in anywhere.