Get rid of seam when baking normals?

I’m trying to bake a highpoly photoscanned rock from meshroom, onto a lowpoly mesh from instant meshes in blender, for use in UE4. My issue is, no matter how I mark the seam/unwrap I wind up with a nasty seam from the normal and I cannot figure out how to get rid of it. What are my options?

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The more jagged your UV seams are, the more noticeable your normal map seams will be. Try to straighten some UV seams and see if it helps.