AS was supposedly staying home with PS who skipped school due to his concussion, so there would have been at least three people in the home or two if AS stepped out and left PS in her care. This is why I wonder how long the kidnapping had been going on and if certain things were a ruse, like that PS didn't really need to miss school where for instance this could have been done on a Tuesday where if PS was at school he wouldn't be there and there wouldn't have been a reason for AS to have been home. Tuesday is the earliest I could see where only one person would be in the home.
It is a huge house with at least two-stories. I doubt AS would leave PS in Vera's care because it wasn't Vera's job to care for a sick child. But it is also possible that the perp waited until seeing AS leave to walk the dogs, run an errand, etc., before breaking in.
Anything possible at this point.
JMO