next of kinnnoun: Refers to person, place, thing, quality, etc.
invariable (immediate family, closest relative)
最近亲属
直系亲属 zhí xì qīn shǔ
My sister is listed as my next of kin on all my emergency forms. The authorities won't release the name of the victim until his next of kin have been notified.
Collins Chinese Dictionary Plus (3rd edition), 2011:
next of kin ['nEkst&v'kIn] (frm)n [u] (=individual) 直系亲(親)属(屬) zhíxì qīnshǔn pl (=family) 家人 jiārén