Family bin

The Family bin is where a Sim family is stored 'in limbo' when they're not living on a residential lot. When you create a family in Create-A-Sim they go straight into the family bin, and from there you can move them into a lot. Telling a Sim to "Find Own Place" also places them in the family bin. The family bin, unlike the lots and houses bin, is neighborhood specific, so you can't move families from one neighborhood to another.

Sub-hoods are the exception, though. A sub-hood attached to a neighborhood shares it's family bin. So, for example, if you attached a Downtown to Pleasantview, any of Pleasantview's inhabitants could go to live in Downtown and vice-versa.