Tracking main/parent domain through add-on domain

I’m currently in talks with my host, I trust them but this is kinda really important to me so I wanted to hear your thoughts

I’m on shared hosting. I want to help a friend set up and probably manage her small site by adding it onto my hosting (as an add-on domain, “AddonDomain.com”). This AddonDomain.com will likely be migrated out later, where I relinquish control and someone else starts to fully manage it on a new hosting plan.

My main issue is that she does not know my websites and I intend to keep it this way, for personal reasons.



All the sites I manage I put on Cloudflare (free).

Please comment on my concerns/questions that follow:

Should anyone attempt to find my main site (“MainDomain.com”) through her AddonDomain.com, they should be unable to because AddonDomain.com…