You can create an unlimited number of synonyms for a single domain. Synonyms are created in the "Domain Aliases." Synonym can have its own unique settings. For a synonym, you can specify a unique DNS-entry (other than the primary domain) and configure logs.
A synonym is created as the primary domain, there is only one difference, this field: "parent domain." In this field, you need to select a primary domain for which you are creating a synonym.
Synonyms NGINX have the same configuration as that of the parent domain.