Siblings are likely to end up at separate primary schools as strict new school zones come into force at a number of Auckland primary schools this year.
The Ministry of Education has contacted 10 state schools concerned classrooms are likely to be overcrowded after unprecedented roll growth.
Several schools, including Green Bay Primary, Arahoe School, Peninsula Primary, Freyberg Community, New Windsor Primary, Owairaka District, Owairoa and Stanmore Bay, are consulting parents about who will automatically be welcome.
Other Auckland schools have been told to reduce catchment areas.
Hundreds of children could be affected by the move, with Green Bay Primary confirming the parents of 45 children due to start at the West Auckland school will need to make new arrangements.