Cruelty to animals violates the law. She was cruel. My children, at six would never have mistreated any animal in such a way. Your sister has big issues that should be adressed by a professional child psychologist. This is intolerable and cruel, to the tortoise and to you. Her act was...
I advise Russian. Red foots have specific humidity requirements, and Leopards are tricky too. Russians are more adaptable, and much smaller. Leopards are quite large by comparison.