The BSB and Account Number are available in the ‘Spend’ tab in your kid's profile.
If you are on an older version of the app, you will need to tap the button ‘Show details’ on the ‘Spend’ tab. Please update the app so you are on the latest version.
Save the details in your banking app so you can make a transfer whenever your kid needs it. The first transfer may be held for 24 hours for security purposes, but after that it should be instant, or close to.
If you do not want your child to be able to see the card numbers, BSB and Account Number, you can tap ‘Manage’, then ‘Hide card numbers’.