If a customer starts the process for a custom domain by himself (maybe this should be defined by user roles in general) -> after setting the DNS records the customer can finish the process via the button "connect your domain" - after cliking the button there is a pop-up with the following text: "we will move your lindo subdomain domain to your custom domain"

For the white label solution it would be good to write something without the word lindo. like: "we will move your current subdomain domain to your new custom domain"