How to create a secondary comcast email for myself, NOT add another user?

I've seen this question posted but none of the responses have actually answered the question of how to.
Simply, I want to create a secondary comcast.net email address for myself without adding another user, without adding another phone number, because there isn't one, and without involving gmail, which I shouldn't have to. (and why wouldn't Comcast want its customers to only, exclusively, use their server?) We're supposed to be able to create seven individual comcast.net email addresses with a simple option to "Create New Email" and where is that option located? This shouldn't be this complicated. Thank you.