Unfortunately, Facebook has changed many things on access permissions (since their legal issues) and now, we can't retrieve any friends contents. It means we can no longer create friends books, multi-accounts books, or lovers books. We know that is disconcerting, but it's not a willing from us.
Of course, you can ask Facebook to let My Social Book retrieves those data for their customers. If customers complain about that, maybe they will accept it.
But
you can offer the My Social Book Experience with a My Social Gift Voucher.