How can I define custom LOD groups?

This Is the Actual answer to the question. Its is just necessary to add “[StaticMeshLODSettings]” at the end plus the “Custom” LOD Grou.
ex.

[StaticMeshLODSettings]

Custom=(NumLODs=3,LODPercentTriangles=50,PixelError=10,Name=LOCTEXT(“CustomLOD”,“Custom”))