I know June moved a few feet from the bed. I doubt she was screaming. She had been shot seceral times. In the head and throat. It's doubtful Sheila or the twins would hear June. They were asleep in other rooms with their doors shut.
My video has what looks like a very similar rifle and silencer to the the ones used. Unless you can find a video of the exact same massacre rifle being used loudly with a silencer, you have to accept it.
The dog was either barking, in another room, or cowering somewhere underneath the bed, where it was found. Either way there is no reason why it would wake the sleeping twins and Sheila. Who were in other rooms.