My heart goes out to you. You have a full household and a lot of people adjusting. But congratulations on your marriage! Now comes the hard part…
Here is the deal, just based on your words: DH’s kids are not doing well. I know we sort of have a cultural attitude of “teens are teens” but let me give it to you straight, as a person who teaches and mentors adolescents: happy teens do not get in trouble with the police, steal, or do drugs. If they are doing that stuff, then they are struggling. And if divorce and blending families isn’t hard enough to deal with, trust me, a spiteful parent who is/was drug-addicted IS. No one wants to hear one parents badmouth another parent and no one wants to watch their parent get wasted. No teen wants to feel like they have to grow up and be responsible. Your DH’s kids need help.
I’m not sure who has custody–DH or his ex or both (sorry if I missed it)–but IF DH has custody or joint, then I am a strong proponent that if you can handle it financially and emotionally, you need to open your home up to his children, if at the very least part-time. And the reason I say that is because SOMEONE has to offer these kids a stable, supportive environment. All kids–including teens–need rules and limits, so it’s a good thing that you and your DH are united in the “no alcohol, no drugs” etc. policies. Don’t be surprised if they break the rules becuase that’s also what kids/teens do; you just have to reassert yourselves through your reactions, through discipline.
These kids specifically probably need consistency. You can offer that both by being ironclad as to your rules and the consequences of breaking them (teens will be crazy dramatic about those rules and consequences, but psychologically, they will benefit from expectations and responses being predictable), but also by being the consistent source of love and support. It’s a tough balance, and trust me–it will be incredibly tough to continually offer love and support in the face of what they will dish out which may be outright rejection. With angry teens, you have to understand that they will repeatedly lash out at you in ways that will be incredibly hurtful. But I stress again–there’s a difference between excusing that behavior (which you should not do), and in understanding it. You and your DH are the adults, and the kids are just kids, so you are the ones who are going to have to put out your hands and offer love over and over, even if they spit at you instead. Your job is to let them know that it’s not okay to spit, but at the end of the day, you ALWAYS keep offering. That’s what unconditional love is about.
Now, of course, saying that is one thing; doing it is another. I’m no Dr. Phil here, so I can’t tell you whether that’s going to be right or fair to YOUR children who also need attention and love as to whether or not the kids can move in with you. And YOUR role in this as the stepmother is also more complex because you don’t have a say in how these kids are raised.
I think my point in writing this is just to help you realize that these kids are in trouble. Understand that they are in trouble and they are now your family and act accordingly.