As far as I was able to determine, there is no public API open for binding or opening contacts, at least in the iOS 6 SDK. However, it looks like you can create links between contacts by calling the undocumented private function bool ABPersonLinkPerson(ABRecordRef from, ABRecordRef to) . This signature may not be entirely correct - I have not tested it too carefully.
Your application, of course, is unlikely to be approved if you use private APIs, but if you are trying to, say, create a fake address book for unit testing and you need some related contacts, this can be useful.
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