In Apple Contacts, you can add a relationship to contact. There is a drop down for label with "mother", "son", etc. Then there is "All Labels" which has a ton of relationships.
In US, separating out "younger sister" is weird, they probably should collapse the list. But in others like Chinese, some of the collapsed relationships have different words.
In US, separating out "younger sister" is weird, they probably should collapse the list. But in others like Chinese, some of the collapsed relationships have different words.