I know how to get friends using my app using Graph API:
me/friends
returns the list of friends using my app.
I also know how to check if two friends have any mutual friends, too (I've asked this question before: Determining if two app using users have any mutual friends in Graph API 2.0/2.1?):
{user_id}?fields=context.fields(mutual_friends)
returns my mutual friend count and list of mutual friends using the app.
However, I need a list of friends of friends who use the app. I can first get all my friends (the first query above) and check if I have mutual friends with them by querying the second endpoint that I've provided above for each user. But for example, if I have 50 friends on my app, it means querying Facebook 50 times, which is definitely not an acceptable behavior. I have privacy settings in my app which contains "friends of friends" option. How can I get all friends of friends using my app in a single query (or at least, not an O(n) query).