Step Daughter problems (need advise)

Yes she finished school barely by going to a alternative school to graduate. She has no car now because she trashed both of them. And my wife is definately a enabler because I'll lay down the rules and then after a few days she lets the **** start all over again. Also my wife and I travel alot and when were gone she has poeple in the house when shes not suppose to and **** always comes up missing. It's just putting a real stain on our relationship and I'm sick and tired of all the bullshit.