In this case you have to use cPanel's feature called "Parked domain". Siteground allows unlimited number of parked domains which you can point to your primary one.
For more information please check the parked domain article of our cPanel tutorial:
http://hostlantern.com/clients/knowledgebase.php
cPanel is easy to work with when you have the right host to support you. If you need a reliable partner to help you manage your website with cPanel, check out our cPanel hosting services!
