It's not easy to be on good terms with one's child's in-laws.
Tips
usage
The qìng reading is reserved for the in-law-by-marriage sense and is essentially bound — you'll meet it almost exclusively inside 亲家 (the reciprocal bond between the parents of a married couple), 亲家公, and 亲家母. Get this wrong and 亲家 sounds like qīnjiā — which most listeners will silently correct, but the swap is a tell that you learned the word from a textbook rather than from in-laws.
history
Chinese kinship terminology distinguishes blood and marriage with separate readings of the same character — a feature that fell out of most words but persisted here because the parent-of-my-child's-spouse bond was socially central in marriage negotiations. Compare 直系血亲 (zhíxìxuèqìng) in older legal language vs the modern everyday 直系亲属 (zhíxìqīnshǔ, blood relatives) — same character, two tracks of meaning.
Components
ideograph
亲qìng
close; relative; parent
Visually unified nine-stroke silhouette: a 立 cap over a 木-like bottom, no longer transparently decomposable. Historically simplified from 親 by dropping 見, combining sharp/grow with see to suggest 'one whom you see often = close relation.' Indexed under Kangxi #117 立 (stand) by tradition via the upper cap.
Filed under radical 立 (lì, #117) by convention. 立 is not a separate component in 亲, so no strokes are highlighted.
