For the family losing its functions you talk about Functionalism and Parson's functional fit theory:
In pre-industrial society, the extended three-generational family was a multi-functional unit; it was a unit of both consumption AND production as they all lived together and worked on agriculture in their own village.
Movement from pre-industrial to modern industrial society has meant that the geographically and socially mobile workforce is needed. This is where the two-generational nuclear family steps in. The nuclear family has lost functions and has boiled down to two irreducible functions:
-Socialisation of the young: teaching them the norms and values so that they are equipped with the skills needed to enter the workforce.
-Stabilisation of adult personalities: when workers return home they can release their anger and tension, enabling them to return to work the next day feeling refreshed and ready to work - it is functional for the economy.
I don't think it would come up as a 24 marker though - there isn't enough to write.