You can't set up separate sites for existing mapped domains. The multi site needs to be a mapping of a separate domain to a start page.
Often most of the time people use subdomains or other full domains.
Are you on the DXP? Is so Optimizely need to set up the domain with you for any new added domains, you'll be best firing a support request to them and they can guide you. If you're on your own infrastructure you just point your domains to the instances you host on or load balancer / gateway.
We had a development agency set up an instance of the CMS with the view that it would be a multisite CMS. They have not provided any documentation or training and will not do so unless we pay additional costs. We have one website live and we would like to spin up another site within the CMS.
Our current website has the url as follows (where xxx is a client id):
I have searched the episever/optimizely user guide and it doesn't cover this in the manage website section.
My questions are as follows:
Thank you in advance