What is the difference between a mother-daughter home and a legal two-family?

A mother-daughter home usually means a house with a second kitchen or living space built for a family member, without necessarily being registered as a separate legal dwelling unit with the county. A legal two-family has been permitted, inspected, and zoned as two distinct units, which is what actually allows separate rental income or two-unit financing. Brian checks permit and zoning records before treating any listing's extra living space as legally separate.