title: Inheriting the Parent Cookie in an iFrame
body: <p>We use a product at my company that allows us to embed secure forms on non-secure sites to transfer information. We do this through embedding an iFrame.
  We use <strong>Google Tag Manager</strong> for most of our clients, and we have a module for tracking submissions of these forms. However, because of it being in an iFrame, every time we submit a form, <em>the source of the traffic is a referral from the parent website</em>, the one loading the frame, not the source of the traffic, throwing our analytics off.</p>
  
  <p>More information:</p>
  
  <ul>
  <li>We're using cookieDomain set to auto on all pageviews and events</li>
  <li>GTM is installed on both the page loaded in the iFrame, and the page loading the iframe.</li>
  <li>Pageviews are currently set to track on All Pages except for the domain the iFrame is on, but I've tried setting it to All Pages and it still tracks form submissions as a referral.</li>
  </ul>
  
  <p>Tl;dr Form is in an iFrame. I land on a page with this iFrame from Facebook. When I submit the form, the source is the page with the iFrame, not Facebook. I want the source to be Facebook. How can I pass the cookie from the parent page to the iFrame, where the event occurs, within GTM?</p>