Here is a quick model of an overbuilt roof using Chief Solids.   Here is a pic, and a very simple plan file.  I actually had more trouble working without my default settings than doing the roof framing.  Just thought a few folks might like to kick the tires.   Edit:  Just noticed that I did not meet the valley plates at the top.  Long day.  BTW the framing is on layer "Framing Roof Rafter Cal Overbuild" Cal Overbuild - Chief Solids.plan