double gable roof panes

[ta2four]

I'm using Home Designer Pro 2014.
In general my plan uses 9' ceilings.
In part of my plan (master closet and master bath) I want to have 8' ceilings as there is no need for 9' ceilings.
The master closet and master bath are on one end of the house. To avoid a complicated roofline, I want to create a gable roof that cuts across my plan where the 9' ceiling meets the 8' ceiling.

How do I accomplish this?

When I generate the roof it looks like this:


I want it to look like this:


(Incidentally, I generated the second picture by creating two separate buildings - they are not really joined.)

Thanks,

Tim