YOU SAID:
your dad is my mom and my stepsister is your son
INTO JAPANESE
あなたのお父さんは私の母であり、私の義理の妹はあなたの息子です
BACK INTO ENGLISH
Your dad is my mother and my sister-in-law is your son
INTO JAPANESE
あなたのお父さんは私の母であり、私の義理の妹はあなたの息子です
BACK INTO ENGLISH
Your dad is my mother and my sister-in-law is your son
That didn't even make that much sense in English.