Why can't we manipulate children of Parallax Node?

[nbtthief]

I have a ParallaxNode, i add few other nodes as children, now i want to change position of one of the child node. For Ex:

auto p = ParallaxNode::create();

    for (int i = 0; i < 1; i++)
    {
        auto rock = Sprite::create("rock.png");
        rock->setAnchorPoint(Vec2::ZERO);
        p->addChild(rock, 0, Vec2(0.5f, 20.5f), Vec2(450*i, ground->getContentSize().height));
    }

    for (int i = 0; i < 1; i++)
    {
        auto rock = Sprite::create("tree.png");
        rock->setAnchorPoint(Vec2::ZERO);
        p->addChild(rock, 0, Vec2(1.5f, 0.2f), Vec2(120*i, ground->getContentSize().height - 10));
    }
    this->addChild(p);

    //p->runAction(MoveBy::create(30, Vec2(-1000, 0)));

    auto c = p->getChildren();
    auto n = c.at(1);
    n->setPosition(visibleSize.width / 2, visibleSize.height / 2); <= hope a child node will be set at the center of the screen, but nothing happen

The only method to manipulate is using _parallaxArray like this tutorials:

[Cocos3.0 Tutorial] Infinite parallax scrolling with primitive shadows

Infinite Parallax Node Introduction Parallax in its general meaning is a changing of object position relative to the background that depends on observer position. Since it is characteristic of three dimensional world it is widely used in two dimensional games in order to create effect of depth. In cocos2d-x there is a ParallaxNode that provides scrolling of its children faster or slower according to the parallax ratio. [Parallax] On the picture you can see that distance between point 1 and 2 d…

auto po = (PointObject*)_parallaxArray->arr[i];
 // If yes increase its current offset on the value of visible width
    if(po->getChild() == node)
      po->setOffset(po->getOffset() + Point(visibleSize.width + node->getContentSize().width,0));

But in this case, we need to create another PointObject class inherit from Ref class to work correctly.

My question is is there any other/better method ?