NSContacts - how to get linked contacts from a unified contact ?

Hi,

In my address book, I have unified contacts for some people :

- one card is with personal data, and is shared with my family with a iCloud account

- for the same person, one card is business oriented, with business data, on another iCloud account

I develop a program with xCode, in swift.

I want to access the contact from the business side, but I am only able to get a unified contact ; when I remove it, I remove both cards.

How can I access the linked contacts from a unified contact ? Or how can I access only one of the linked contacts ?

I currently use unifiedContactsMatchingPredicate (with predicate predicateForContactsInGroupWithIdentifier) which fetches only unified contacts ; I could not find another method more appropriate !

Thanks for your help,

Nicolas