Plural of “daughter in law” [duplicate]

Question

Possible Duplicate:
Words that are pluralized in the middle?

I was asked to write the plural of daughter in law in an aptitude exam. I wrote it as daughters in law. Please tell me the right answer.

Answer 1

You are right.
When pluralizing words like "-in-law" or "-in-chief", The noun is pluralized, not the modifiers following. Hence:

"Fathers-in-law" not "Father-in-laws"

and

"Commanders-in-chief" not "Commander-in-chiefs"

Answer 2

A handy link is available at http://www.ehow.com/how_5620678_spell-plural-fatherinlaw-similar-words.html.

1. Always connect the parts of these family nouns with hyphens (-) in both the singular and plural. Thus we write "father-in-law," "sister-in-law" or "brother-in-law." It is not considered correct to write them without hyphens.

2. Form the plural by adding "s" to the noun, and not to "law." Thus we can write, two "mothers-in-law" and three "sisters-in-law." These are the correct forms even though native speakers may not use them.