I have looked at the Children's bedroom photo many times, but today I noticed something else. Kate has always maintained that everything was quiet in the apartment when she returned at 10pm, she listened at the Children's bedroom door and all seemed fine. But then she noticed the door was slightly more open than how they'd left it, which indicates to me that the Children wasn't checked at all that night. So Kate opens the door slightly and see's the Twins sleeping.

One of the cots is blue and has a mesh type fabric covering all sides, the other cot is brown and has the same type of mesh fabric, but it only covers the side panels on the cot, the head and foot panels are covered in brown fabric that you can't see through.
Kate pops her head round the door and see's two sleeping babies in their cots, she wouldn't of had a problem seeing the baby in the blue cot, but seeing the baby in the brown cot would have been impossible unless she was about eight feet tall.
So Kate McCann has seen the two babies in their cots without entering the room and in the dark.
Well I done my own experiment, I put a large box on my bed and the further I stepped away the less I saw what was inside and further more, if a Child was going to be abducted that night surely they would have taken the Child that was out of view and not the one that was in plain sight, thus giving them more time to make their getaway. I suspect Amelia was sleeping in the brown cot.
Just an observation
1) You are assuming that despite several people moving around that room, searching and checking windows shutters etc., then removing the twins to take elsewhere with their bedclothes, that nothing got moved? That is a big assumption and may, or may not, be correct
2) The Twins cots have very low sides. The bed is a cheapish bed and low as can be seen on various photos. The bed only comes up to the upper end of the second drawer of the chest, and the twins travel cots only come up to the lower edge of the upper drawer ... so maybe 4"-5" higher than the low bed?
3) The photograph is taken from a low level. You can see the door knob.
4) All these facts show that the travel cots had very low sides. Kate is tall and IMO would have no problem seeing the twins in these travel cots from the doorway. Especially so as the only one with a blanked end was quite close to her
IMO, Kate could see straight into these travel cots from the doorway. One big step into the room and she could have seen madeleine, had she been there.
Yep, Robin, the room was fairly dark inside but with the shutters up, a small amount of light would have been coming in via the window, and some light would have been beaming in onto the brown cot especially from the lamp that was left on in the sitting room. Madeleine, around the corner, would not have benefitted so much from the light from the sitting room