Is it possible to setup domain1 so that it is simply an alias for domain2?

In other words:

- I have 3 domains: myemail.com, myemail.org, and myemail.net that I want to be administered in unison rather than independently.
- I want to create myemail.com as the primary/default domain, and myemail.org and myemail.net as pseudonyms for myemail.com so that anyuser@myemail.org and anyuser@myemail.net are automatic "aliases" for anyuser@myemail.com. It would also be nice if it is not even actually possible to directly create an account for user@myemail.org and user@myemail.net.

(I'm not in command of all the jargon.. is this domain "aggregating", "masquerading", "forwarding"?)

Thanks!