That's a good point, and there might be a court case about that. I agree that the parent probably doesn't have enough free choice. If the law was to say "That isn't freely given", then the school doesn't have consent, so they can't use the images!. That's the beauty of it. It's a different legal viewpoint than "signed contract uber alles". DPA should look at if you had real consent.
> it is clear that this would be viewed as being antagonistic towards the school and its interests.
Good? The whole point of the GDPR & EU data protection law is to push the pendulum the other way, because it's gone too far. If someone can come up and force them to reprint everything, and then someone else force them to reprint everything, well maybe they should collect less personal data? If they didn't collect personal data, they wouldn't have this risk. EU law is trying to discourage massive data collection.