I have this same question (6 years later), but I'm not seeing the answers to to CdnGuy's questions. It looks like "Solver" responded, but those posts aren't here that I see.
I have an even more basic question too though. To accomplish a balloon frame structure, with rafters that create the 4' exterior wall, with ceiling joists at 8', do I define a second floor in Home Designer Pro or just go to the Wall Specification Structure Panel from the 1st floor view and choose the "Balloon Through Ceiling Above"? I'm not sure how to accomplish this "2nd floor" (or attic?) building structure with it's 6 sides. Is the attic actually a 3rd floor?. I'm 6 days into learning the program. Thank you!