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Brooke is an adult and she needs to be held accountable for her actions. Does Brooke own up to her stealing? Maybe a police report needs to be filed. If Kim has established house rules and Brooke refuses to abide by those rules, then she must be given an ultimatum and be required to live elsewhere of else her actions may become more untolerable and negative.
On the flipside... if all family members are willing, family counseling or therapy would be another completely different alternative to work through these difficult issues.
Your sister will have to decide what would be the best option for her that she could live with.