Questions on material definition of parallel geometry

Hi :
I recently ran into a problem regarding the definition of materials in parallel geometry. According to the manual:Even if specified a valid material pointer, unless “layered mass geometry” switch of the
G4ParallelWorldProcess constructor is set, it will not be taken into account by any physics process.

So in my project I added the following code

//--------------------------------------------------------------------------------
G4Material*    ssMaterial =
    G4NistManager::Instance()->FindOrBuildMaterial("G4_Galactic");

G4Torus*test = new G4Torus("test",0.2*mm,0.25*mm,10.25*mm,0*degree,90*degree);
  auto*testlv = new G4LogicalVolume(test,ssMaterial,"test");
  new G4PVPlacement(
    0,
    G4ThreeVector(),
    testlv, 
    "test",
    testboxmother,
    false,
    0
  );

//--------------------------------------------------------------------------------
DicomDetectorConstruction* theGeometry = new DicomRegularDetectorConstruction();
auto*parallelWorld = new GB06ParallelWorldForSlices("ghostworld");
      theGeometry->RegisterParallelWorld(parallelWorld);
      runManager->SetUserInitialization(theGeometry);

auto*phys = new DicomPhysicsList();
  phys->RegisterPhysics(new G4ParallelWorldPhysics("ghostworld",true));
  runManager->SetUserInitialization(phys);
  runManager->SetUserInitialization(new DicomActionInitialization());
  runManager->Initialize();

I inherited G4VUserParallelWorld in my code and defined the parallel geometry and the material of this body in Construct(). Next I defined the name of the parallel world in the main function via GB06ParallelWorldForSlices().

After that use G4ParallelWorldPhysics() in RegisterPhysics and define the second parameter as true. According to the manual:If “layered mass geometry” switch of the G4ParallelWorldProcess constructor is set, that parallel world is conceptually layered on top of the mass geometry.

I would like to ask the experts whether the way I defined the parallel geometry material in this way is correct. And there is a sentence in the manual:that parallel world is conceptually layered on top of the mass geometry. I am not sure how to interpret this statement, it means that this parallel geometry if it successfully defines the material then is he not covered by the material in the mass geometry?

I want to know if I define a parallel geometry is placed in the mass geometry and if I define the material of the parallel geometry then the positional relationship between the two bodies will be changed, even though they appear to be contained positional relationships in QT.