Wallet C (actually it was the first one that I created) contained all 3 seeds, I didn't know that was possible.
I assumed when creating a wallet and you insert the 3 seeds, it would store the first seed and compute the public key of the other two and store them.
Fair enough, the option doesn't have the same message in "
Enter consigner key" where it's explicitly noted that putting a "
master private key" will enable you to sign for that particular cosigner.
The "
Enter cosigner seed" option is listed an another option without a note.
That may actually confuse someone who's new to Electrum or Bitcoin in general.
-snip- It's confusing the UI is showing the "main seed" and not the others.
It's noted with the message "
Your wallet generation seed is:" because that's created when you make that wallet.
The seed phrases of the second and third cosigners are created by their respective wallets.