Add/link a child to an account

The support section offers guidance on how to add/link a child to an account but this does not appear to apply to Riftbound accounts specifically. The URL of the support page has carde.io rather than riftbound.uvsgames and the screenshots look like a different UI/UX, so I presume there are differences between the functionality on the different accounts; e.g. there isn’t a ‘guardianship’ section in my account page. The child account is now unable to go any further without linking to a parent account but this does not appear to be possible so we’re at a roadblock.