@Revengeofthepangolins
Thanks for your response. Your comments pretty much echo my own thoughts (especially on PIL's shooting themselves in the foot - though on the flip side it's perhaps better to face this now rather if he got an offer and ended up there).
I think what you've said here is probably the way to go:
"If he continues to be so public spirited, point out that most offers won’t be made until Jan so he isn’t blocking a place. "
Basically buy some time and get DH (or possibly me as I tend to be more tactful, but don't misunderstand that I wouldn't be clear) to have a word with PIL's in the meantime.
Honestly they are lovely people and are devoted to their GC's but I think they just haven't got the message that independence is a key part of the Uni experience (in fairness, unlike my DP's neither of them went to Uni so I think they see it a bit like "extended school" and not as a more rounded life experience).