I am using a Samsung Galaxy On7, Android 6.0.1. In the latest update (released April 2018), they have added a feature such that you can store your social media content on SD card, but link it to the internal storage. For example, Whatsapp still doesn't support reading the SD card. If you enable the "Move to SD card" option, the phone will move all Whatsapp data from internal storage to SD card, but these will still be accessible when you open Whatsapp.
I know about the Link2SD app, which creates a second partition on SD card and treats it like internal memory. But here there is no such partition created. How does Samsung make this link? Is there any app available that can do this same thing (the app may ask for superuser access, I have no problem with that).