Facebook does not have multi-image posts. So, GAIN creates an album with the photos and then a timeline post sharing the album.
When an album is created on Facebook directly, they create an automatic timeline story that lets people know about the new photos. These timeline stories are generated by Facebook and we have no control over them. For instance, on timeline stories, we can't set audience targeting or visibility.
Basically, we instruct Facebook to generate a post linking to the newly-created album so that users on GAIN can have control over their multi-image posts.