Jokes aside: Does this phrase particularly allude that Hans is attracted to our sister romantically or that his like for her could be platonic? Or can it be used both ways and meaning inferred? Thanks!
The other one would be used if you are contrasting, e.g. Hans mag nicht meine Schwester, sondern meinen Bruder "It's not my sister whom Hans likes but my brother / Hans doesn't like my sister but rather my brother".