Whoever scammed the person 100k, it was forcibly taken from your account, you or your sister, if you share the account you share responsibility for it, the fault for one there is the fault for both of you. If she got on your account then you should have secured it better. You cant get your money back and you would need to earn it back up yourself. I am sorry but it was both yours and your sister fault since you did not secure your account and she used it without your permission, your sister has no account therefore you cant sue her or anything. I suggest maybe talking to her not to do it again, or totally not let her use your account by logging out after using it and change the password if she knows your password. This all I can go to help you, it was your sisters fault and we can't get 100k from her since she dosent have an account, I suggest talking it out with her, maybe tell her to play for you and tell her to mine resources worth until 100k as her punishment, sure I guess it sounds a bit rude but maybe you can try under your supervision. Its really all up to you to make a solution to it but I highly doubt you will get your 100k as it was your sisters fault and you cant get anything from her.