A possible solution is to create a Custom Profile in the Profile Manager and assign it to a Wall or Beam.
Then draw that Wall/Beam along the Roof edge you want to see as custom.
Then perform the necessary SEO between the custom profile Wall/Beam and the Roof.
This Wall/Beam can reside on a custom layer which is hidden and wireframe. This way you will only see the result when you hide its layer.
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