Hi Muse
I'm sorry your dad's unwell and hope the op is successful. It's unlikely that the HLC will be there as they should have addressed any questions with the surgeon/anaesthetist before hand, but only if your father felt that necessary. My experience of the HLC has been that they are unobstructive, pleasant men who are well intended but hopefully you'll be saved from the irritation of their presence.
My father died when he was 60, the day after an operation in which he lost a significant amount of blood, and while the medics never explicitly said that the loss of blood triggered his heart attack, some of our non JW family felt that it must have. My opinion is that it was his choice and his belief and he knew the consequences and now that I'm no longer a JW I would still respect his wishes.
s man