"{domain name} or one of its subdomains is already managed by Netlify DNS on another team."

[SamO]

Sure, to prove you own a domain you need to set a txt record which links to this thread. Instructions are below.

[Support Guide] "another site is using this domain" Verifying domain ownership for Netlify production domain

Last Reviewed by Netlify Support Staff: September 2023 Are you receiving the error “another site is using this domain” when you are trying to add your production domain to your netlify site? Read on! This is easy to fix. This occurs when you are trying to add a production domain that already exist on Netlify under a different account. Do you know who might be using the domain (maybe a previous collaborator or an agency you’ve worked with in the past?), the quickest way to get this resolved i…