Curved rafter construction

Are there any recommendations for constructing a mansard/gambrel type curved roof. I was told to scribe and cut the curved part out of a 2x12 and attach it to the bottom straight rafter using pocket screws. The other technique I heard was to sister two pieces of scribed/cut 2by12 to the straight rafter with a plywood gusset, but this would use excess lumber. Anyone familiar with other curved rafter techniques?

i have worked on a number of 80 to 100+ year old houses and replaced old framing members. does not make me an expert.
there is usually a full sized structual straight rafter with the curved added on top or sistered to it. in newer constuction i have seen them cut out of double 3/4 ply with a ton of bridging.
curves are typically a waste of material and man hours thats why they cost $$$. sure do look nice though.
goggle “framing complex gambrels” it should show pics