Common knowledge among whom?
Mrs Fenn, an independent witness, said she heard the McCanns enter via the patio door on 1st May having heard MM cry for 1.25 hrs. This supports an unlocked patio door being the door used for checking.
I wonder if any conversations took place among T9, either face2face or behind closed doors, about the McCanns decision to leave the patio doors unlocked?
So you have convinced me that Mrs Fenn knew they were leaving the patio door unlocked. So when she complained to her friend and to others possibly how many others got to know about the unsecured apartment?
Did the staff at Tapas Restaurant know that the McCanns were checking via the patio door? If they knew did they tell any other OC or MW staff member?
You ask: "I wonder if any conversations took place among T9, either face2face or behind closed doors, about the McCanns decision to leave the patio doors unlocked?"
Well in my theory they did.