vtkResliceImageViewer

Hello, I want to perform MPR on my 3D volume and display the 3 planes (axial, coronal and sagittal) in one render window. Problem is that, if I want to change the cursor (and update the other 2 views) in the upper plane I can’t because the mouse takes the red line of the lower plane, so that I have to rotate this line (figure 2) if I want to move the cursor of the upper plane.

Now I can move the cursor of the upper plane

How can I do so that the red line of the lower plane ‘exists’ only in the lower viewport?
This is the part of the code I think I need to fix:

  vtkSmartPointer< vtkResliceImageViewer > viewer = vtkSmartPointer< vtkResliceImageViewer >::New();
  vtkSmartPointer< vtkRenderWindowInteractor > interactor = vtkSmartPointer< vtkRenderWindowInteractor >::New();

  interactor -> SetRenderWindow( viewer -> GetRenderWindow() );
  viewer -> SetupInteractor( interactor );
  
  viewer -> SetInputData( reader -> GetOutput() ); // pipeline

  viewer -> SetResliceMode( 1 ); 
  
  viewer -> GetRenderer() -> SetViewport( xmins[0], ymins[0], xmaxs[0], ymaxs[0] ); 

  vtkSmartPointer< vtkResliceImageViewer > viewer2 = vtkSmartPointer< vtkResliceImageViewer >::New();

  viewer2 -> SetRenderWindow( viewer -> GetRenderWindow() );
  viewer2 -> SetupInteractor( interactor );
  
  viewer2 -> GetRenderer() -> SetViewport( xmins[1], ymins[1], xmaxs[1], ymaxs[1] );  // questo viewer verrà visualizzato in alto a sx

  viewer2 -> SetInputData( reader -> GetOutput() );

  viewer2 -> SetResliceMode( 1 );

  // make them all share the same reslice cursor object.
  vtkResliceCursorLineRepresentation *rep = vtkResliceCursorLineRepresentation::SafeDownCast( viewer -> GetResliceCursorWidget() -> GetRepresentation() );
  viewer -> SetResliceCursor( viewer -> GetResliceCursor() );
 
  rep -> GetResliceCursorActor() -> GetCursorAlgorithm() -> SetReslicePlaneNormal( 2 );
 
  viewer -> SetSliceOrientation( 2 );
  
  vtkResliceCursorLineRepresentation *rep2 = vtkResliceCursorLineRepresentation::SafeDownCast( viewer2 -> GetResliceCursorWidget() -> GetRepresentation());
  viewer2 -> SetResliceCursor( viewer -> GetResliceCursor() );
 
  rep2 -> GetResliceCursorActor() -> GetCursorAlgorithm() -> SetReslicePlaneNormal( 1 );
 
  viewer2 -> SetSliceOrientation( 1 );

Thanks in advance for any help!!