Upgrade adoptable USB storage in Android Marshmallow

Yeesh!

I'm writing this guide for myself because I can't find much on the Internet about this. I haven't even tried this, I'm making it up as I go but trust me this is going to work or there will be blood.

1. Install App2SD on the phone
2. Backup app list using App2SD
3. Disable USB debugging (if necessary)
4. Set the USB mode to MTP (if necessary)
5. Plug the phone directly into a PC (no USB hub)
6. Browse to the SD contents:
   
   • If you are using Windows or a Mac, just do it
   • In KDE look in Dolphin's "places"
   • If you use GNOME put on your big boy pants
   • If you use Unity, check yourself into rehab
   • Or see ₂
7. Copy the SD contents to the PC₁₂
8. Switch off the phone
9. Replace the old SD card with the new one
10. Boot the phone
11. Tell Android to delete the old SD card and pray
12. Format and migrate to the new SD card
13. Reboot the phone
14. Copy the backed up data to the new SD card (I needed a File Manager and AirDroid for this)₂
15. Re-install App2SD
16. Use Superman strength to replace the App2SD backup with the actual backup₃
17. Use app restore in App2SD to manually confirm to install each and every missing app
18. Reboot the phone
19. Put everything back to normal. 99% of apps will have fully restored data, use Superman strength for the 1%
20. Try not to kill anyone

Easy huh?

Update

I'm thinking my OTG cable could have really helped with this.