why would the party be asking about the other members?

Look up old time writer Damon Runyon. His short stories inspired the musical 'Guys And Dolls.' He wrote about Times Square and the showgirls, gamblers, crooks, bar flies, social workers, servers, bouncers, general riff raff, and hoi polloi that he'd seen.

It's common in his stories for people to strike up a conversation with a stranger and ask about what's going on. Even a small time hustler will be known by sight, and a stranger in town is evaluated.

Also, remember that when you ask A about B, A is telling you a lot about themselves. In 'Stranger Things,' the boys warn the new girl that the town is full of bullies, which tells her that these are the kids who get bullied.