How to view the results of parallel geometry

Hi geant4ers:
Hello experts, I have recently been using the DICOM example to test a radioactive seed I designed, which I plan to implant into a model created by DICOM as a way to simulate the radiotherapy process. I followed Ms. guatelli’s suggestion to simulate this implantation process through parallel geometry to avoid the problem that the G4PVParameterised parent can only have a unique child.
I managed to build a test box and place it successfully, and when the program runs, I get this message on the terminal

Parallel World `parallelWorld’ constructed.
— G4CoupledTransportation is used

I was thinking that maybe the parallel world was created, but I can’t see the created box in the results displayed by QT.
Here is the program I used to create the parallel geometry

  G4VPhysicalVolume* physicalParallelWorld = GetWorld();
  G4LogicalVolume*    logicalParallelWorld = physicalParallelWorld->GetLogicalVolume();

  //get back the logical volume of phantomContainer

  G4LogicalVolume*Containerlv = G4LogicalVolumeStore::GetInstance()->GetVolume("phantomContainer");
  G4Box*Containers = (G4Box*)Containerlv->GetSolid();
  auto*testboxmother = new G4LogicalVolume(Containers,nullptr,"testboxmother");
  auto*testboxs = new G4Box("testboxs",5*cm,5*cm,0.5*mm);
  auto*testboxlv = new G4LogicalVolume(testboxs,nullptr,"testboxlv");
  new G4PVPlacement(
    shieldPhysical = G4PhysicalVolumeStore::GetInstance()->GetVolume("phantomContainer");
   G4ThreeVector translation = shieldPhysical->GetObjectTranslation();
   new G4PVPlacement( nullptr,                           // no rotation
                     translation,                       // translate as for the shield
                     testboxmother,            // its logical volume
                     "motherForSlices.physical",        // its name
                     logicalParallelWorld,              // its mother  volume
                     false,                             // no boolean operation
                     0);                                // copy number

  auto visAttributes = new G4VisAttributes(G4Colour(1.0,1.0,1.0));
  visAttributes = new G4VisAttributes(G4Colour(0.0,255.0,0.0));

I am truly looking forward to the answers and opinions of all the experts here, you have no idea how precious even a word would be to me. Here’s wishing you all a happy life.