Getting form's parent data with ajax / javascript

In CRM DYNAMICS 2013, I'm trying to get the contents of a few text fields of a parent form, after a user opens a child form.

On the OnLoad event of the child form, I have this code:

var objvsdsassignedto = document.parentWindow.parent.parent.opener.Xrm.Page.data.entity.attributes.get("address1_line1");

The error I get is:

I have also tried:

var objvsdassignedto = window.top.opener.Xrm.Page.getAttribute("address1_line1").getValue();

The error I get is:

How do I get the contents of fields using the child form?

here's a larger version of the screenshot above: http://ift.tt/1xIuSYV

Just wanted to update this question with more of the things I've tried:

var objvsdsassignedto = window.parent.Xrm.Page.data.entity.attributes.get("address1_line1").getValue();
var objvsdsassignedto = document.parentWindow.parent.parent.opener.Xrm.Page.data.entity.attributes.get("address1_line1");
var objvsdsassignedto = window.top.opener.Xrm.Page.getAttribute("address1_line1").getValue();
var objvsdsassignedto = parent.window.Xrm.Page.data.entity.attributes.get("address1_line1").getValue();
var objvsdsassignedto = window.parent.Xrm.Page.getAttribute("address1_composite");
var parentWindow = window.dialogArguments;
alert(  parentWindow.Xrm.Page.data.entity.attributes('address1_composite').getValue());
var parentForm = window.top.opener.parent.Xrm.Page.getAttribute("address1_composite").getValue();
alert(parent.window.Xrm.Page.getAttribute('address1_line1').getValue());

var title = window.parent.opener.Xrm.page.ui.controls.getAttribute('address1_composite').getValue();
alert(title);