How to assign a different custom/subdomain for a fork?

Hi, I have a fork in v0 in the same project with minimal changes that I would like to deploy under a different custom/subdomain to be able to do a A/B Test. How can I do this?
I tried already downloading and copying it into a new project, but things get lost on the way so this is no solution for me.

The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for bonus points.

You can also use v0 to narrow down the possibilities.