https://km-3d.com/produkt/deltamush-skin-plugin/

DeltaMush to Skin is a c++ 3ds Max modifier which smooths deformations while preserving details with “converting” to Skin feature. The plugin solves Skin weights matched as close as possible to the DeltaMush result. It enables the user to export such rigg to the game engine like Unity, Unreal etc. The whole process is incredibly fast thanks to multithreaded optimization.