Move Family from Gallery to ‘Other Household’?

If you're pulling the households straight from the gallery or your library while you're at the manage worlds screen, then you need to move them in, evict them, and uncheck the heart.

If you go into CAS first and then load up the family into CAS, then upon exiting CAS all you have to do is click the "X" when prompted to have them move somewhere and it'll accomplish the same thing. Whichever method you go for merely depends on convenience.