Changing LDAP user source ZCC

Hi,

I want to change ZCC to use my new LDAP server. Cause i want to shutdown the old LDAP server.
I can only add a new user source and not change a current user source.
What do I have to do now? if i delete my old user source and add the new one do i lose my relationships?

Keeping the old and adding the new LDAP server isn't an option:
Unable to complete your request for the following reason: A user source already exists for the specified directory.

Cause they both use the same tree.

What to do in this case?