Import of FBX having LOD gives unexpected result

I’m trying to import an FBX file into Unreal, the file is created in another software using FBX SDK. After importing it into Unreal, the scene tree order is not retained. Following is the FBX SDK code I used to export to FBX.
FbxNode *lLodGroup = FbxNode::Create(pScene, “LOD_01”);
FbxLODGroup *lLodGroupAttr = FbxLODGroup::Create(pScene, “LOD_01”);
lLodGroupAttr->AddDisplayLevel(FbxLODGroup::eUseLOD);
lLodGroupAttr->AddThreshold(FbxDistance(500, FbxSystemUnit::mm));
lLodGroupAttr->AddDisplayLevel(FbxLODGroup::eUseLOD);
lLodGroupAttr->AddThreshold(FbxDistance(1000, FbxSystemUnit::mm));
lLodGroupAttr->AddDisplayLevel(FbxLODGroup::eUseLOD);
lLodGroupAttr->AddThreshold(FbxDistance(1500, FbxSystemUnit::mm));
lLodGroupAttr->AddDisplayLevel(FbxLODGroup::eUseLOD);
lLodGroup->SetNodeAttribute(lLodGroupAttr);
for (int j = 0; j < lChildNodes.GetCount(); j++)
{
lLodGroup->AddChild(lChildNodes.GetAt(j));
}
Can you kindly let me know what is the correct way to create LODs through FBX SDK and import them into Unreal?