I need some Advice or Ideas for my castle

[Bogie]

I am mapping a castle from an old AD&D module for a private user.
As often is the case with those classic maps, they look good until you start looking close at the details. The way rooms and items are drawn are often not to a realistic scale or don't really depict what is there.

In this case, my problem is that rooms 1, 2 & 3 would logically extend under catwalk 4 all the way to the castle wall. The original map does not show that but I want my map to at least try to address the issue.

So my question is, How do I make it look like the rooms on the ground level extend under the catwalk above them?
My only solution I could think of is to use a partly transparent line to depict the wooden walls. Any other Ideas?

If the lines are the best fit, then do you like the dashed lines or the solid one?

The map is being created in DundJinni, but can be touched up in Photoshop.

Thanks for any and all advice.