alternative CNAME

Hi,

I'm new to FG, I have some public domain a.y.com that is being accessed from our office. That domain is actually a CNAME to some other domain. The CNAME is defined publicly on CloudFlare.

Now, for some migration purposes, I want to know if I can use FG to change that CNAME, so that the same a.y.com, if accessed from the office, would point to some other public domain - while other subdomains like b.y.com, c.y.com will still be resolved as usual without being overridden

Is it possible?

Thanks!