Hi, @timboslice, before we can proceed please delete the inactive DNS zone at Netlify here:
Once that is done, then delete the branch subdomain under Site Name > Settings > Domain management > Branch subdomains.
Finally, create the branch subdomain CNAME record as described in this support guide:
Please reply here when that is complete and our support team will extend the SSL certificate to cover this subdomain. If there are any questions about this, please let us know.