There was one stairway which was quite narrow, and I could find it going down to 5 deck, but whenever I wanted to go up, I could not discover it as it was hidden around a corner somewhere. (I swear she was laughing at me trying to find it) But what stairway could it have been.
Once I have finished all my assignments, I will dig up my deck plans and try to work it out. Sorry I have no stairway pix, did not think to take them.