How to manage a domain for a friend with the correct WHOIS details?

I manage a domain for a friend, both technical (DNS etc.) and billing. But friend should be the legal owner of the domain name, so I want to use a correct WHOIS profile. If I add the domain to my own Cloudflare account this doesn’t seem to be possible. Ideally I could create multiple WHOIS profiles and attach the desired one to each domain.

What’s the correct way to do this curently? Should I create a separate Cloudflare account for myself, where I fill out the friend’s WHOIS info? Am I allowed to have multiple accounts or would I get flagged for fraud or something?

Separate accounts is SOP for some who manage sites for others. You’ll need a unique username/email for it.