12 years old is about the age for being rebellious. You can start locking up your valuables as you mentioned that your family financial is tight and they are for bills. If she keeps taking them, then you will have a hard time trying to pay the bills.
You should sit her down and talk to her about the severity of the situation with your husband. Use another approach instead of confronting her. It will be a big problem if she starts stealing out of the house. If there is no choice, perhaps it will be better to contact social services. Better have them hate us than see them landing themselves into something more serious.
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