Fehwalker

A customer I provide backup MX for has registered some of my hosts under his name, and now when I try to activate Mailhosts for my account it's lumping all my other mail hosts under his pre-existing entry - ie, when I view my mailhosts it's showing his name. Can this be changed? If I delete the mailhost entry will it delete it for him as well? Is it possible for Mailhost entries to not overlap for different users like this? Thanks, Bryan