What does a 'family' mean when buying an LNER Family Return ticket?

For the purpose of the LNER Family Return fare, a family is defined as being between a minimum of 1 adult and 1 child (aged 5-15 years old inclusive) up to a maximum of 2 adults and 4 children (aged 5-15 years old inclusive). The group size must be specified when you buy the ticket. All tickets required for travel must be bought at the same time. By the way, you don’t all need to be related!