YOU SAID:

my mother loves to cheat on my brother with my sisters cousin

INTO JAPANESE

母は妹のいとこと兄をだますのが大好き

BACK INTO ENGLISH

Mother loves to trick her sister's cousin and brother

INTO JAPANESE

母は妹のいとこと兄弟をだますのが大好き

BACK INTO ENGLISH

Mother loves to trick her sister's cousin and brother