Adding levels to Penthouses

aparments use special room markers  in buy debug and removing restrictions in building mode

check out this tut http://simswiki.info/wiki.php?title=Tutorials:TS3_Sims_3_Apartments#Building

Thanks a lot but it isn't exactly what I need. I am not building apartments - merely editing them via edit town. I saw this link: http://forum.thesims3.com/jforum/posts/list/283202.page  I don't understand what the person means by merely "drawing a box around it" in this paragraph:

'Move your Sim out and make sure you still have those cheats. Each building I've tried to modify so far has had a potential of two levels in addition to the one that's already been designed, for a total of THREE USABLE LEVELS OF SPACE. Usually, the other two levels aren't built, so you can go and add those manually by just drawing a box around the level that's already there.' 

I know how to add a floor up but am wondering if it is possible to add a floor down as the camera skips roughly about 19 floors in the One Leo Centre in Bridgeport. I don't know how to stop the camera from jumping; I did see a thing on removing all the floor tiles and grabbing hold of the level skip marker - does anyone know?

Thanks again.

the camera issus is this

How do I get rid of it though? By removing all the floor tiles and trying to grab it?

Will make a post in the Creative Corner. Thanks so much for your help - I'm accepting as solved but will post in this thread if I get an answer on the forums. 

Thanks again!