According to reports, Shannon was the only adult there, and she was inside busy with little one, and no doubt the ‘house duties’.It doesn't seem possible anybody could sneak up on that property, unless they knew the occupants routines and where they would be later in the day, making an approach from behind the main residence using the outbuildings and sheds etc as cover.
Or they snuck in at night and stayed hidden through the day but then if abduction was the purpose, not only do they have to get in unseen but they also have to get out.
Also the house seems to have heavy brick columns all along the covered front verandah area, so it could be reasonably soundproof inside
JMO.




