Each game account requires a unique Supercell ID. Therefore, to transfer all your game accounts to Supercell ID you need as many valid email addresses.
To attach your first account to Supercell ID:
Configure your device with the correct Google or Game Center account.
Open up the game. The account associated to your Google account or Game Center will load.
Open Settings and tap ”Disconnected”. Then select ”Register New”. Follow the instructions on your screen.
Please note that only the latest verification code sent to you will work.
After your first Supercell ID has been created:
Configure your device with the correct Google or Game Center account for your second game account.
Open up the game. The account you just attached to Supercell ID will load. Enter settings, tap on ’Connected’ and then tap on ’Log out’.
The game will restart, and you now see a menu in the loading screen. Tap ’Play without Supercell ID’. The account from your Google or Game Center account will now load.
Create a Supercell ID for your account.
Repeat these steps for all your accounts, and be sure to keep ’Remember on this device’ checked! It's also worth noting that whenever you're asked for a verification code, only the latest verification code sent to you will work.