gōa-ke-chhin外家親

relatives of a king or emperor on his mother's

relatives of a king or emperor on his mother's or wife's side

English Wiktionary, “外家親” (CC BY-SA 4.0) — https://en.wiktionary.org/wiki/%E5%A4%96%E5%AE%B6%E8%A6%AA · confidence: Medium (Wiktionary)