I have a website with different domains and I'd like to have some domains to have different languages.

I have a main site which is example.com, it's the main "group" site, it has multiple languages, in this case french, english, russian and spanish.

Then i have several other "sub" sites assigned to other domains and each have one or many assigned languages. For example: es.example.com is in spanish ru.example.com is in russian

The problem is for a sub site that have more than one language. for example: ca.example.com would be in french and english.

How do you configure drupal to be able to achieve this, and how do you make the language switcher display only the languages available on the domain ?

I have domain access and i18n installed obviously.

Thanks in advance for your help.