By Whom, Singular nouns

Grammar Geek wrote:Let's see what other people think. Which of the following are acceptable? Which are outright wrong? Situation one:Of all the nice young ladies we just met, which would be good candidates to join our Tea and Cupcake Society? Correct, as an interrogative pronoun, which is used...

Dear sir, I have some inquiries about the choice of noun form (singular or plural) to be used with a plural possessive determiners (their, our, etc.) I have sought the advice of some native speakers on the following 4 sentences only to become more confused as they have different opinions. It is...