Best practice changing primary custom domain with branch subdomains still used


I’ve got a project that has two different custom domains attached to it. Let’s say and Currently the primary domain is and some branch subdomains are created, like and they are actively used.

Now if I want to change the primary domain to be, so future branch subdomains will use that domain instead. How will I keep my old branch subdomains active, so the transition can happen over time?

If I setup Automatic deploy subdomains with, and switch over the primary domain as well. Will the old branch subdomains remain pointing do Or will they switch over to as well?


Ideally, you should create a separate site with the same setup and add the new domain there. This way you can easily keep both sites and domains active.