Just go ahead and take down the stolen art. It's a major crime and we don't care if you say your sister drew it. there is no way in hell that you or your sister drew it because there is a link proven that the art was traced / done over. take it down, because if someone finds out your info, you have a high chance of the following "shall be fined under this title, imprisoned not more than 10 years, or both." Yeah, legally speaking you can get jail time for that shit. so delete it and just admit you're wrong.