What you can do now:
Export selected parts with Dicam 1-1-6
Import them into a new building with 1-1-7
After doing so, all these parts will belong to free construction MOS.
You cannot export wall bodies and roof faces, but you can export all beams and and parts.
"Dormer with construction" as macro we had in former (DOS) times, and it shall come again, at least I heared so.
"Normal roof": Instead of working with dormers, you can (optionally) create new ground floors with their own walls and roofs. Theu will automatically cut with the main roof.