The man was a broom salesman, hit on the head with a hammer and put in the cupboard.
The lady in the fridge was given some poisoned lemonade to drink.
Skekayuk has covered the boy in the cellar pretty much so.
There was also a fourth victim. I think another male Whatnot who was put into the attic.
We don't know his personal story. Marissa just sang so if you come to our house, I forget what she said they would do but they would end up putting you in the attic. With your very own personal roomate already there for company. Isn't that nice?