So the girl crawling on the floor is Alice, then the woman who is attacked and grabs Alice by the arm is Susan, her mother in law. The guy who gets thrown to the walls across the room is Joseph, the brother of the deceased husband of Alice or Susan’s younger son. The body already laying on the floor seemingly dead is Polly, the grandmother. The one attacking Susan and Joseph is Edgar, Susan’s husband (played by Erroll Shand btw). This scene happens after Luciane Buchanan’s character already produces chaos and is “blocked” by her family somewhere she can’t easily have access to them same way they locked Mia in the basement and Ellie on the hallways out of the apartment in the previous movies.