The claim that entrance was made via the sliding door to avoid waking the children was in the documentary 'Madeleine was here'.
The problem is this explanation does not tie up with the statement:
http://www.mccannpjfiles.co.uk/PJ/GERRY-MCCANN-10MAY.htmsnip
----- That they left the house by the main door, that he was sure he locked,
it being that the rear door was also closed and locked. They were the first to arrive at the TAPAS where everyone showed up except only for MATHEW, who was still ill.
---
They entered through the front door on this night.
By the Wed 2nd the statement states:
----- On Wednesday night, 2 May 2007, as well as he and his wife, he thinks that DavidP also went to his apartment to confirm that his children were well, not having reported to him any abnormal situation with the children. On this day he and KATE had already left the rear door closed, but not locked,
to allow entrance by their colleagues to check on the children.---
i.e. the rear door was left open to facilitate 'entrance by their colleagues to check on the children.'
DavidP categorically denied making any checks on the children in his rogatory statement.
The Wed 2nd is also the night of the 'crying incident'.
What all this means is not clear to me, but the status of the doors through the week is an open question IMO.