YOU SAID:

when the owner took the dog on the walk he brought his second cousin with him

INTO JAPANESE

飼い主が犬を散歩に連れて行ったとき、彼はいとこを連れてきた

BACK INTO ENGLISH

he brought his cousin when the owner took the dog for a walk

INTO JAPANESE

飼い主が犬を散歩に連れて行ったとき、彼はいとこを連れてきた

BACK INTO ENGLISH

he brought his cousin when the owner took the dog for a walk