IMO it was obviously staged - but to make time to do that you would need a very good reason.
Not getting caught after the event is surely a good enough reason. How long would it take to open window/shutter? He/she would know they had some 30 mins based on the pattern of McCann visits.
Why would the abductor - need to make it look like an abduction.
The abductor wanted to make it appear that he/she was unaware of the unlocked patio door.
Why did the mcns think it was so safe to put twins back in the creche.
Why not? MM wasn't abducted from creche. She was abducted from 5a which had an unlocked door and was unsupervised.
When for obvious reasons in your post - it could have been anyone close to home.
Not sure what you mean by anyone close to home?
Why did the mcns trust everyone in that complex - at a time you would trust no one
Not sure they did trust everyone. KM states in book words to the effect she was dismayed everyone was able to leave ie fly home as planned.
Especially your acquaintances/friends - who knew the children were in an unlocked room alone.
McCanns probably ruled out T7 on the basis they knew them well and trusted them plus they didn't have time to abduct MM and dispose of her body. You're right others should not have been trusted that they met on hol. It comes down to prejudice ie middle class families playing tennis wouldn't abduct children but many have the potential. Consider the paedophile doctor from Cambridge:
https://www.bbc.co.uk/news/uk-england-cambridgeshire-34591633