Relative positions in coco studio, how to access them in the code?

Hello, I’m testing out the relative positioning in cocos studio, I have a simple layer with relative positioned items in it (see screenshot). I’m using the same setup as in the sonar tutorial about supporting multi-resolutions.

Now when I look into the json file from coco studio, the relative positioning is there. The ‘prePosition’ is what I need

But when looking at the loaded childs I can’t find this property. Is there a property I’m missing? Or missing some steps in general to enable relative positioning?

I’m using coco studio 2.2.6 and cocos2d-x js 3.9 btw. The code to load the json is

 loadCocoStudioFileWithRelPos: function(file)
{

    var winSize = cc.director.getVisibleSize();
    var origin = cc.director.getVisibleOrigin();

    var loadedFile = ccs.load(file, this.getCorrectPath());

    var children = loadedFile.node.getChildren();

    for (var i = 0; i < children.length; i++)
    {
        var child = loadedFile.node.children[i];

        //which property do I need?
        var relPos = child.getPosition();

        relPos.x *= winSize.width + origin.x;
        relPos.y *= winSize.height + origin.y;

        child.setPosition(relPos);
    }

    return loadedFile;
},

So how can I access the relative positioning in the code?