Okay, having taken a quick look on Mumsnet (not my favourite place, but just for the purposes of research), it seems many people DO take rentals for a short periods of time to get into schools then move out. So they think all that disruption and expense is worth it? And ongoing hassle of the child commuting and not living near any of its friends? And teaching them a very dubious lesson about it being okay to lie to get what you want? This is so sad.

It also seems that councils are checking up on this, though, and can withdraw offers of places to children whose parents are in a short-term rental and own property elsewhere. So maybe this sibling policy is a good idea in some cases. But I do hope that schools take it on a case-by-case basis and don't penalise parents who have no choice but to move.