I am very sure that under these circumstances - in the UK - if you contact the holiday resort, and tell them that you all potentially have Scabies, and one of you actually has got it, but that you all feel well enough to still go on your holiday, they will tell you that you absolutely can't go, and they would probably offer alternative dates for the holiday, or agree to give at least a partial refund.
I have had to cancel 3 holidays in the past because our dog wasn't well, maybe I could have got away with sending him to the kennels by pretending he must have come down with something after he was left there, but I would have never done that, one reason being that it wouldn't be fair to the other dogs there, or to the kennel staff, and the other reason being that I would never make my poor dog be away from us and home, when he was already feeling rotten due to his illness.
Luckily, when we had a holiday of a lifetime to Florida, our dog wasn't ill, but if he had been, we would have cancelled, and lost thousands of pounds when doing so, as I don't think that travel insurance would cover one's dog being ill. I don't think that I/we are special Sesma, I think that any decent human being would do the same. Are you, and apparently @melonhen not decent human beings then?