A non-destructive breakline does not remove any triangle edges. It places new points along the breakline at each intersection with a triangle edge and new triangles are computed. Again, it is created like standard breaklines are created except you call the AeccSurfaceBreaklines.AddNonDestructiveBreakline method.
Set oBreakline = oTinSurface.Breaklines _ .AddNonDestructiveBreakline( _ oEntityArray, _ "Sample Non-Destructive Break", _ 1#)