@James-And-Jane0
Third party booking for a young minor? No ** way.
I went to boarding school. There was always another student's family living nearby, a teacher, or a small apartment on campus where students in this position could stay when they couldn't go home for a holiday, were suspended for some kind of serious hanky panky, or for other reasons. I hate to be mean but if NO one at the school is willing to house her then I don't it's a safe idea to do so yourself (even if the rules let you).