How to modify or override the normal of Groom hair in Unreal Engine?

Development Character & Animation
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1

I’m experimenting with stylized hair rendering and would like to customize the normal direction of Groom assets.

From what I understand, the default Groom shading model computes strand normals procedurally in the shader, based on tangent, curve direction, and lighting. However, I can’t find any way to override or inject custom normals — unlike meshes, Groom doesn’t expose normal data or custom attributes when importing Alembic.

So my questions are:

  1. Are Groom normals fully generated internally at render time with no way to customize them?

  2. Is there any supported workflow to supply custom per-vertex/per-strand normals or extra attributes from Alembic?

  3. If not, is modifying the Hair shading model the only option to achieve stylized “surface-like” lighting (like the effect in the movie “The wild robot” by Dreamworks)?

My goal is to make Groom react more like a continuous stylized surface rather than thin physical strands, so being able to control normals is important. Any guidance or recommended workflow would be greatly appreciated.

Or should I use a card-based method instead if I need more control over the hair rendering?