Because I do not think Angie would have trusted the men to do things right. Her character would not have allowed her to release control completely to them. I think the boy was asleep in the vehicle and when they went to Dana's they either took SW out before or after the killings. I think SW was sleeping in bed with Hannah.
jmo
JMO, I believe, the phone call, Dana received at work was from Hanna. Saying dad, is not answering, his Phone. ( Do to it being hacked.) saying Jake, was coming over to take SW. When Dana got home, the Wagner's, was already their. I believe they was waiting, when she got out of the car. And the, thought they was asleep in their beds was staged, to make it look like a drug hit.
No one stayed home with the kids. The young boy with the cow name, was with the family, he need to be with the clan, when they took SW. These people do not, think like normal people. And it was just a night out with a new adventure, in their eyes. A family that teach their children when their young, that this is a way of life, and what they consider normal.
I have seen no proof, either way if this was their first time, out killing. I think they might have tried with a smaller number, then 8, on their first killing adventure.
I still believe, AW had a affair with someone that was killed. And Billy, was always told we was not a success with out being on moms teet. Why can't you be like Chris?
AW, I am sure could, convince Billy, to do as he was told. And when she sent him home, to live with FW, he better come not come back, with out some money.
All my opion, no facts.