procedure CopyCollision(aSource, aDestination: string);
var
  SrcNif, DstNif: TwbNifFile;
  node, bhknp, bhk: TwbNifBlock;
begin
  SrcNif := TwbNifFile.Create;
  DstNif := TwbNifFile.Create;
  try
    // load meshes
    SrcNif.LoadFromFile(aSource);
    DstNif.LoadFromFile(aDestination);

    // add NiNode as a child of the root node in destination mesh
    node := DstNif.Blocks[0].AddChild('NiNode');
    // copy NiNode data from source mesh
    node.Assign(SrcNif.Blocks[12]);

    // add bhkPhysicsSystem first because it must be before bhkNPCollisionObject
    bhk := DstNif.AddBlock('bhkPhysicsSystem');
    // copy bhkPhysicsSystem data from source mesh
    bhk.Assign(SrcNif.Blocks[3]);

    // add bhkNPCollisionObject
    bhknp := DstNif.AddBlock('bhkNPCollisionObject');
    // copy bhkNPCollisionObject data from source mesh
    bhknp.Assign(SrcNif.Blocks[13]);
    // set Target field pointing to NiNode
    bhknp.NativeValues['Target'] := node.Index;
    // set Data field pointing to bhkPhysicsSystem
    bhknp.NativeValues['Data'] := bhk.Index;
    // set it as a collision for NiNode
    node.NativeValues['Collision Object'] := bhknp.Index;

    // save destination mesh
    DstNif.SaveToFile(aDestination);

  finally
    SrcNif.Free;
    DstNif.Free;
  end;
end;