Enroute to the stated goal in my question I was reading this and step 6 reads
"Under Primary Domain on Hosted Site, click Change Domain."
I don't see that anywhere on the page, how do I find that?
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You go to your Hosting manager, not the domain manager and one of the big buttons is 'domains'. You can assign domains or subdomains to subfolders from there. You need a deluxe account if you want multiple domains on the one bit of hosting.