Hi @warren.harrison,
In your Action script, you can use the Management API’s Update a user endpoint to update the user’s given_name and family_name. For more information, check out our knowledge article at Using the Management API in Actions.
Additionally, you will find our ManagementClient | auth0 reference useful. Specifically, you will need to call the management.users.update() method to update the family_name and given_name root attributes.
Thanks,
Rueben