Whenever they open their mouths 
Yeah in this regard...

So lets dig out the fine tooth comb

and do a bit of analysing
1 Why is there mention of what door Maddie may have wandered from? the simple answer is the unlocked one ofcourse! Occams razor and all that.
2 why did she leave the apartment? was she instructed by parents to go get them if something was wrong? did she wake up and knew the door was unlocked?- who knows there are many reasons.
3. why would the parents leave a door unlocked and then use a locked door to do their 'checking' hmm?
4. why would the parents instantly dismiss the
walk and wandered theory- to protect themselves from the law? - as they left the children all alone all evening, many evenings, and with an unlocked door, no physical checking at scheduled times how would they explain that one ?
5 Why would a burglar not use the unlocked door to enter and exit- if he she was 'watching' the apartment.
6. why would the parents tell a story about an abduction via a small bedroom window-which was only noticed when one parent claimed to have known the exact measurement of the door from the previous person checking? (the father)- who left and stood outside the apartment and within seconds an abductor jemmied a shutter grabbed a child and ran off,only to be seen by a friend.
As the saying goes you couldn't make it up... but then... In My opinion that is exactly what I believe- they made that up.