According to VMware Cloud Foundation documentation, once a VI workload domain has been deployed as an isolated domain (with its own SSO), it cannot be reconfigured after deployment to join the management domain’s SSO domain. The official guidance states that the only supported approach is to delete the incorrectly configured VI workload domain and create a new one through SDDC Manager, ensuring it is properly configured to share the SSO domain with the management domain during the deployment process. There is no supported process to convert or migrate an existing isolated SSO VI workload domain to a shared SSO configuration after deployment.