YOU SAID:
I like your sister not you
INTO JAPANESE
私はあなたではなくあなたの妹が好きです
BACK INTO ENGLISH
I like your sister and not you
INTO JAPANESE
私はあなたの妹が好きで、あなたが好きではない
BACK INTO ENGLISH
I like your sister and I don't like you
INTO JAPANESE
私はあなたの妹が好きで、私はあなたが好きではない
BACK INTO ENGLISH
I like your sister and I don't like you
That didn't even make that much sense in English.