We run a platform that acts as a one-stop warehouse of user's interactions with a brand, both through apps (campaigns etc) and through the pages run by the brand. So far, the linking up of facebook users across apps and page-posts was simple - since facebook passed you global facebook ids.
With v2.0 of Graph API, and the migration to app-scoped-id, a brand can still connect the app-scoped-id from various app-authentications through the /ids_for_business api call. When User's log into the app, they are considered authenticated and hence the mapping between app-scoped-ids works.
For posts pulled from the Facebook pages through the API, the "users" are considered non-authenticated, and hence the mappings through /ids_for_business call skip the app_scoped_id listed to page-post-pulling-apps.
Is there a solution to map such users into their app-scoped-ids issued to other apps under the same business account?
Alternatively, is there any other way to reliably map such users across apps and page posts?