Another poster said it was illegal not to be in school there, ive not checked this out personally though. They must be doing/saying something to get around it
And with them buying the land and building their house....surely the authorities know they are there with their kids not as tourists.
You'd hope someone would notice that said kids were not enrolled at any sort of school especially if it is genuinely illegal
Maybe it's like the uk & us (& other places) where people can be home-schooled but most people actually go to school rather than it being flat out illegal and they're managing to get round any sort of checks