Hi Mala, I'm not sure if this is what you need but it is possible to use Construct > Curve > Silhouette to make a mold "parting line". You can remove an area of undercut with it.

Construct > Curve > Silhouette can generate these using "Top" as the projection view will generate these curves:





Trim the surface with the silhouette curves:



Project the silhouettes and extrude the projections:



Trim extrusions:



That will cause the shape to drop straight downwards with no area "in shadow" :



- Michael