YOU SAID:

my cousins dad mum is also in the same your room thing as you're the mother

INTO JAPANESE

私のいとこのお母さんのお母さんもお母さんと同じあなたの部屋の事にあります

BACK INTO ENGLISH

My mother's mother in my cousin is in the same room as your mother

INTO JAPANESE

私のいとこの母親の母親はあなたの母親と同じ部屋にいます

BACK INTO ENGLISH

My mother's mother in my cousin is in the same room as your mother