That's the way if you don't want to pay the transfer fee (if you are Gold, you can transfer free some Avios to a HHA member or Friends and Family member). Never done it though...
Or you can try to combine, like pay 1 one-way ticket from your wife's account and the rest 3 one-ways from your account. Must remember that an IB account must be at least 90 old to transfer to/from it...
Also, mass locking of accounts due to Awardwallet access has spread to IB+ now, and although it doesn't say anywhere, the account may be under audit and locked. Any operation will fail without a meaningful explanation, just a general "you are not allowed to do this".