Are there laws surrounding underage children living in detached quarters from their parents?

My 7 year old son just moved to a new house with his mother and her new boyfriend. His mom is living/sleeping in the detached garage with her boyfriend while my son and his two siblings (his nine year old sister, and his 11 year old brother) live and sleep in the main house. I'm uncomfortable with this arrangement. Does anyone know if there are any laws that define this kind of situation in California?