How to Enable Adoptable Storage

Adoptable storage is a feature introduced with Android Marshmallow to format the SD card "as internal". This means that the storage available on the SD card is seamlessly integrated to the internal mass storage of the phone, extending the internal storage by approximately the size of the SD card. Whereas Concept for Z3 offered a special dialogue letting the user choose whether to format the SD card as internal or external (i.e., mounting the SD card as usual external storage), this option seems to be missing in Concept for X.

However, adoptable storage can be enabled via ADB, a rooted device is not necessary. The basic command is. BEWARE: This command will erase all data on the SD card. Please find a detailed tutorial at: http://www.xda-developers.com/enable-adoptable-storage-for-galaxy-s7-and-s7-edge/ This was possible on virtually all devices running Marshmallow and without root.

Things to Consider Before Enabling Adoptable Storage
Backup all your data from the SD card before enabling adoptable storage. As said above, the SD card will be formatted and all data will be erased from it during the process to enable adoptable storage.

By formatting the SD card as internal, an encrypted file system will be created. This file system is encrypted with a key, which is bound to the current Android installation. This means that in case you re-install Android, factory-reset your phone, or change the phone (e.g., due to damage), the data on the SD card cannot be read! Make sure to regularly maintain your backups to not lose your data. (A method to extract the encryption key is described at Android Enthusiasts Stack Exchange. This method however needs a functional Android phone.)

You should bear in mind that if you do this, you run your device in an unsupported configuration. If errors or bugs occur, it's harder to determine the cause in your case because of adoptable storage making life harder for all Concept users, especially the devs.