If you don't nip this problem in the bud, it can mutate into more serious acts like shoplifting. At her age, she is definitely going through a rebellious phase and pushing all sorts of limits.
Stow all your money and valuables in a new location and try not leave your bags and wallets lying around. I know it must be hard, but she broke your trust and tough love needs to be applied. Sit her down and talk about the seriousness of her actions and if there is no improvement, "threaten" to report to authorities.
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