Our API lets you send individual friend list updates from your backend, and we're actually working on a web-hook based way of handling friend requests: if we ne

Our API lets you send individual friend list updates from your backend, and we're actually working on a web-hook based way of handling friend requests: if we need to verify that user A has permission to talk to a new user B we can POST to your web server and then update the friend list, or (if you use Parse) you can specify a Parse query and we'll look up the friends that way.