YOU SAID:

My mother is my mother's mother, and my brother is my sister.

INTO JAPANESE

私の母は私の母の母と兄は私の妹です。

BACK INTO ENGLISH

My mother is my mother's mother and brother is my sister.

INTO JAPANESE

私の母は私の母の母と弟は私の妹です。

BACK INTO ENGLISH

My mother is my mother's mother and brother is my sister.