When referring to in-laws using 義理, do you use the familial term relative to yourself or to your spouse? When using terms such as and , do you choose vs relative to your own age, or relative to your spouses age? If you are older than your spouse, but said spouse's older brother is younger than you, which term is appropriate? I assume the same applies to the word-versions such as ?

Relative to your spouse's age.

In your case, you'd have a () who is younger than you. And you'd be his / who is older than himself.