Smoothing the intersection boundary of two mesh - Questions

Is there a post-processing effect or method that can smooth the intersection line of two meshes? just like this:(smoothing the intersection area of head and neck)

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A localized subdomain smoothing MMALE particle method for efficient modeling FSI problems - ScienceDirect

Noob question. I'm trying to remove material from each section, trying to make something like u carving for each section. Something like the other image. Did I go wrong on how to

Smooth

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Explicit edge-based smoothed numerical manifold method for transient dynamic modeling of two-dimensional stationary cracks - ScienceDirect

Cusp lifetime. (a) Cusps occurs at the intersection of the two

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