Setup custom name servers to use for other domains

I want to know if I can setup custom/private name servers on cloudflare, and then have other domains use those name servers too.

For example I currently have NS1 & NS2 records pointed at a name server I’m using outside of cloudflare, and I have several web design clients using those name servers too setup in their registrars.

So, if I setup my name servers on cloudflare can I also add my clients dns records for their domains too?

(I’m picturing adding a new site, and instead of having the options of only greg and fiona my name servers would be an option too)

Thanks for the help!

Depends on what you mean by “set up”. You can simply create X A(AAA) records, point them to an (unproxied) IP address where your own nameserver is running, and use these records for the other domains. You cannot use the Cloudflare nameservers however.

I’ve read that you can setup custom name servers on an account in cloudflare, and cloudflare provides you IP addresses for your NS records.

But, once I’ve done the above can I use those domain servers with other “sites” that I’m adding to Cloudflare?

Yes, but these apply only to the domain for which they were set up. You cant use them other domains.