Facebook JS Authentication on my whitelabeled domains

I'm redesigning a social auth component in our app. Our app requires user to login via Facebook before any content can be downloaded.

Currently we do server side oauth to download what they need.

Our goal is to have the JS auth, sexy popup without redirections.

Our content can live on 2 different URLS:

• subdomain.app.com, where subdomain can be an alphanumeric string


• anydomain.tld which is an alias to subdomain.app.com. No redirections required, content rendered as if you were on subdomain.app.com

Now I know that JS auth requires "App domains" defined in Facebook app settings. The first type of URL goes through our admin, so they could just add the subdomain to Facebook app settings. However whitelabelled subdomains are 100% in hands on end users and they don't have access to our app.

So my question is, what are my options? Is it even possible, to do what I want without involving humans?

Thanks, Michal