title: How to add multiple facebook callback urls
body: <p>I have a product (eg: somedomain.com) where people can create their own subdomains (eg <a href="http://xyz.somedomain.com" rel="noreferrer">http://xyz.somedomain.com</a>) or even map their domains to it (eg: example.com)</p>
  
  <p>Now, I want to offer a feature so that my customers can enable "Login with facebook" feature into their subdomain.</p>
  
  <p>Since facebook requires us to add a list of URLs under "Client OAuth Settings" > "Valid OAuth redirect URIs"</p>
  
  <p><a href="https://dl.dropboxusercontent.com/s/26tg672ytiorp9f/Screenshot%202015-09-03%2021.44.19.png?dl=0" rel="noreferrer" title="Screenshot">Click for Screenshot</a></p>
  
  <p>What can I do so that it allows my product's subdomain (eg <a href="http://xyz.somedomain.com" rel="noreferrer">http://xyz.somedomain.com</a>) or customer domains (eg: example.com)</p>
  
  <p>Thanks</p>