Hello, how can i accomplish that my list sync makes identical copies both in joomla and mailchimp.

The current situation is like this. I have a sign up module on my site. When a user is registered CMC does receive the registration. My mailchimp is correcty connected with my joomla. When i do the sync between lists, the joomla list receives the names from mailchimp and removes all other that are not in the list in mailchimp.

So to sum things up.
The registration is received in CMC and ends there, if i sync, the list in the Mailchimp is the main one which overwrites the names in CMC.

How can i get that the user registration is written directly in Mailchimp?

If that is not possible, how can i achieve that when i use syncronization the names from CMC get aded to the Mailchimp list and not the other way around or that all the names which are not in mailchimp get erased. The list in my CMC and Mailchimp are simply not identical and i want them to be.

So far the only way i was doing is manualy copying the names from CMC to Mailchimp by using export CSV and importing it to Mailchimp.