I never mentioned anything about another wallet owner. This thread is regarding a single owner setup.
Well, you can do that as well on Multisig wallet.
Just generate a standard wallet and make a backup of that 12-word seed and also the master public key. Now make a Multisig "2 of 2" wallets it will generate a new 12 words seed and then paste the master public key on "Enter consigner key". After successfully generated you must have a wallet with two 12 words seed phrase.
Make sure you have a backup of them for future recovery.