Dongwoo has 2 older sisters, one of them used to live oversea. Hoya said there was a time he saw how Dongwoo called his 2 older sisters and it’s like this: Dongwoo calls his first sister “big one” (큰거) and his second sister “little one” (작은거), but in Korean the word “거” is used for object, not for people. And during the part where Dongwoo said that one of his sister used to live oversea, he used the word “하나” (it literally means “one thing” in the context of Dongwoo’s sentence) instead of “한분” (one person).