Filter Subgrid 2015 Online Update 1 - SetParameter is null

Hi all,

I have my code as advised by this article:

http://stackoverflow.com/questions/32564310/dynamics-crm-2015-online-subgrids-control-setparameter-method-is-not-available

I use window.parent.document.getElementById to get the subgrid reference and it ALWAYS returns NULL even after the setting timeout.

I then tried Xrm.Page.getControl("subgridname").getGrid() to get the subgrid reference which works but then when I use control.SetParameter it returns "unable to get property 'SetParameter' of undefined or null reference"

I do realise this is unsupported but it seems like this is the only way to do it, has anyone got this to work?

My code is:

function GetSubgrid() {
    var relatedOpportunitiesGrid = window.parent.document.getElementById("Pursuit_Team");

    if (relatedOpportunitiesGrid == null) {

        setTimeout('GetSubGrid()', 500);
        return;
    }

    var fetchXml = "<fetch>Fetxml goes here</fetch>";


    if (relatedOpportunitiesGrid.control != null) {
        relatedOpportunitiesGrid.control.SetParameter("fetchXml", fetchXml); //set the fetch xml to the sub grid
        relatedOpportunitiesGrid.control.refresh(); //refresh the sub grid using the new fetch xml
    } else {
        setTimeout('GetSubGrid()', 500);
    }
}