I have Oswald's path marked in orange. There was no door directly behind Adams and Styles.
We seem to be writing at the same time. I had not seen your previous post when I wrote the post you've now responded to. In the meantime I had removed my post again.
As for there not being a door directly behind where the girls were, connecting the office and the storage space, you may wish to re-examine the 4th floor plan used by the WC, because that clearly shows the presence of that door.
Thanks to John for posting the floor plan.