Hello, I have followed this thread a bit out of nosiness if I am honest given the awfully worrying experience we had with DD last year (3 schools, 1 waitlist offer and 2 rejections, one before interview).
I wanted to offer a hand hold to any families without a firm place. Waiting lists can move right up to the start of the school year (appreciate that's not ideal but there is hope!)
I would suggest that if your child is on a waiting list, and you really want them to go to the school, then apart from letting admissions etc know suggest your child writes to the head / head of year 7 and tells them how much they want to come. Best of luck.