Your home, your rules. Have a family meeting with all of the kids and explain what behavior is expected. Then if any kid, biological or step, gets out of line they get the appropriate punishment. You have to keep your word though. If they disobey then it is essential that you and DH follow through with the punishment.

My SS7 used to be like your stepkids. Not anymore, at least at our house. He knows how to push his BM's buttons and wear her out to the point that she gives in. I, on the other hand, have a shit ton of patience and can outlast him every time. I have put him in time out and he has sat there crying, screaming, saying awful things and I sit in a chair next to him reading a book like I hear nothing. He learned very quickly what works at BM's house does NOT work at Harleygurl's house. Things eventually improved.

Time to post YOUR rules for the home and inforce them. If your own DD can behave and follow the rules then it will be your DH's devil spawn who are disciplined and your DD who is rewarded.

Your DH needs to man up and parent his children. Tell him either he steps up or he and his spawn won't get a key when you rekey all of the locks in the house.

IMHO of course.

The children are 2,3, 7 and 8? That's a lot of young children to manage. I'm not surprised there's chaos at times. Although you have children I think that's one area you might find it hard to understand - there is a big age gap between your children so you haven't had to juggle several children at similar and demanding stages, and unfortunately it doesn't sound like DH is making a good job of it. The only way to handle a family of that size is lots of structure, clear rules, and unambiguous enforcement. You can't just have them all milling about and hope for the best. Maybe DH doesn't want to admit he can't cope and doesn't know how to handle them, would there be any scope for getting some parenting help - a course, a book, a good sit down and draw up a rules and routine chart? If DH is misguided and a bit soft but fundamentally a good Dad and able to discipline his kids you may be able to improve things, if he's just going to rely on excuses and doesn't have the commitment to change things then living with those kids as they grow up is going to be hell.

Your DH is at fault here. He needs to set rules and boundaries and have consequences for the kids who don't follow the rules. You should not be made to feel like an outsider in your own home. You should not have to hide in your room. You are the adult, for God sake, and it is your home too. That is just awful.

Did you know the kids were like this before you got married?

You and DH need to sit down and discuss what each of you expect. I know my kids were pretty rambunctious and I was ok with it. (They did not tear up the house though). I would not like it if my new partner came in trying to change everything. Especially since you only see them a few times a month.

Maybe you can do other things on the weekend he had the kids?

I couldn't even imagine being married to someone with a child as young as 3, let alone FOUR kids, and all of them young. I mean, how long could you have had to know him as a father and in a relationship with you with the youngest being 3? Did he even have a minute to help his kids deal with the separation/divorce? I think we expect too much from kids after we put them last on the list in our decisions. Ever notice how often sparents on here have a hard time adjusting, but we never consider what the skid is going/has gone through? I NEVER would have entered this picture. I have reached an age where I know what I'm capable of and what I'm not willing to put myself through. I have two kids, 19 months apart, who have been pretty good kids. I'm not going to put up with someone else's idiot kid being an idiot whether it's maladjustment or crappy parenting. And I wouldn't do that to my kids. I think it goes without saying, I hope you are using 3 forms of birth control LOL

Most times, it's not the kids...it's your spouse. Our family therapist had to tell DH repeatedly that he needed to step up and not leave all the disciplining to me. DH really didn't get it until I started disengaging and he realized just how much he relied on my help. Once he realized that he made conscious efforts to discipline his children and make sure they abided by house rules. I still have to remind him every now and again, but he's human so I am patient.

Yikes, don't hide and no one wants it to end up in divorce.

Talk about both of you co-parenting, meaning there has to be more discipline. Absolutely, I don't care if they are being raised in a barn at their mother's house. You need to make sure like people have suggested to clearly tell them no means no, and after that the consequences will follow. It's the same with any child, they will get it real fast, but be consistent.

Luckily myself and dh never had problems in this area. If he wasn't around, I ran the show. We were the co-parents, and I equally disciplined. If they run, hit..don't you hide...they go to their room until they can act decent.

I'm wondering if there are ADHD issues or other things?? Something to think about because there shouldn't ever be aggression, so watch for that and bring it to dh's attention.

Also, I agree never tell him how you feel about the children because this might be temporary because of their behavior, and it's mostly your frustration. Put it in a tactful way, that there needs to be changes for everyone's happiness. Explain that during those weekend visits you want him to spend alone time with his kids, and he can take them out for activities. And that might be your time to be with yours or at least your youngest. I think that would alleviate all the craziest too. And DH needs to be realistic that the kids may not end up liking each other or get along. They may need to be separated more, and that's not a bad thing.

Or when they visit take your children to a show, or out for those days. Be honest and tell him since you work, you needs your time too.