How do I use my own custom domain and stackbit to depoy sites to subdomains?

I am currently using stackbit to build a site and host on netlify. I have a custom domain registered and name servers are pointing to netlifydns. The issue is that my site is deploying to my domain and I want to deploy it to a subdomain. And also other sites to other subdomains. Basically I want each project in stackbit to point to a different subdomain. Project 1 in stackbit => site1.my.domain, Project 2 in stackbit to site2.my.domain, etc.

How do I do this?

If you want Netlify to serve your website on a sub-domain, connect only the sub-domain to Netlify. For example, instead of adding my.domain, add site1.my.domain to the Domain Management section.

However, at this stage, you’ll have to make some changes. First, remove Netlify nameservers from your registrar and revert them back to default. This will let your registrar control the DNS instead of Netlify. Then, remove the current domain from Netlify. Finally, add the sub-domain with guidance from here: Configure external DNS for a custom domain | Netlify Docs

Let us know if you’ve any additional questions.