The visit to the apartment block by Russel O'Brien and Mathew Oldfield at about 9:30pm, is very interesting for a number of different reasons, since, there was no access to their own apartments by way of the patio doors, because these had been locked from the inside and therefore Oldfield and O'Brien could only access their own apartments (5B and 5 D) by way of the roadside doors on the far side of the building away from the tapas bar, pool and restaurant...
Oldfield's apartment door, 5B was next door to the apartment where Maddie and the other two children were supposedly sleeping, and at around 9pm, Oldfield had listened at the bedroom shutter of 5a, when checking on the kids, so why did he listen at the patio door on the poolside of the building when he went back at 9:30pm?
Which route did O'Brien take?
O'Brien would have to use the door on the roadside of his apartment (5D) to check on his child, so he would be on the right side of the building to assist in the removal of Maddie from the apartment (5a), in my opinion...