Yuxin may have done this more than once. From her past experience of hiding this in such a long duration, she might be more diligent and hide more Chinese Currencies in any section she can reach from. I suggest that look through her room, stuffs, etc and without telling her is better for future references. (Use Chinese Translator or if someone is Half Chinese & American, translate, please and thank you very much in regard.)
Stealing is wrong, but instead of how much she has stolen, I believe a more serious question is why she did it. There could be deeper issues that result in the stealing behavior from both ends.
