Multiple domains and alias

Multiple domains and alias

I added a new domain to my subscription plan.
There is no option to add an alias as the help and forums suggest.
Not under 'Mail Accounts' and not under 'Domains'

I am only able to receive emails from my new domain after I added a 'catch all' of new domain going to my old domain.

Is this the correct setup?

It works but just doesn't seem right.