관계대명사절 범위와 in 용법 질문드려요

“We would need to do studies in which individuals are sampled in terms of their dream life and judges are asked to make correspondences between these dream events and events that occurred in real life.”에서 관계대명사절은 어디까지인가요?
관계부사로 바꿀 수 있는지, in은 왜 쓰였는지도 궁금합니다.