FBXImportHardEdges -v [true|false];
Merges back all vertices located at the same exact position as a unique vertex. The Maya FBX plug-in then determines if the edges connected to each vertex are hard edges or smooth edges, based on their normals.
Use this function when FBXExportHardEdges is set to True on export.
This command is the script version of the Combine per-vertex Normals option in the FBX Importer. See Combine per-vertex Normals for more information.