Those pesky in-laws

My brother and his wife have been married almost three years. Naturally, her parents are his in-laws. His father-in-law and mother-in-law, more to the point. My question is this: Since he is their son-in-law, and his wife is my sister-in-law, does that technically make her parents MY father-in-law and mother-in-law, as well? My sister would have the same parents I do (unless she is a stepsister or a half-sister). What would be their offical relation to me? How should I address them if referring to someone who doesn’t know them? Would I say “my sister-in-law’s parents?”

Your sibling’s in-laws are not your in-laws. You would say either “I’d like you to meet my sister-in-law’s parents,” or “I’d like you to meet my brother’s in-law’s.”

I would like you to meet the people who raised a woman without any taste, sense, or standards. The woman who married my brother.
That’s how I would phrase it.

“My brother’s in-laws” (or “parents-in-law”) would do nicely, as it’s more directly descriptive of their relation to you.

What can be confusing also is one’s wife’s brother’s wife is also your sister-in-law, as well as your wife’s sister-in-law.

E.g.,
Tony == Val – David == Tina

“==” is a marriage, “–” is a sibling relation.

To Tony, David is a brother-in-law and Tina is a sister-in-law
To Val, David is a brother and Tina is a sister-in-law

This only works if there’s one sibling relationship in the middle.
E.g.,
Michelle – Tony == Val – David

David and Michelle are no relation

My wife’s brother’s wife and I refer to each other as the out-laws. My wife also has a married sister, but her husband is a jerk, so we don’t give him any title beyond “sister-in-law’s husband.”