You mentioned step dad stuff. My step dad and I *never* got along in my teenage years. We tolerated each other. Finally had the beginnings of a brawl in the kitchen once over the dishes, too.
Love the guy to death now. Glad he didn't give up or back down. But even if I would have ended up hating his guts for life, he made sure I knew he didn't care... He was going to do the right thing and make me do the right things whether I liked him or not.
He knew he was at a disadvantage. At the end of the day mom might cave and tell him to back off, making me think I "won", if he pushed it as far as my real dad might have done.
Family counseling highly recommended. No experience raising kids here, but experience being in a house with two step kids and the baby half sister of both from the two adults in the house. Various dynamics going on there, and I can almost guarantee it'll never be quite "normal".
I'd defend my step sister and my half sister's lives well into personal jeopardy today, as would I defend both mom and my step dad and take care of them.
Step families are always somewhat dysfunctional. No avoiding that.
I have a bad feeling one or both adults are undermining each other's authority somehow too. As a kid in that scenario I didn't even have to try hard to see how to manipulate one side against the other. Neither did my sisters when we all grew up and talked about it later. They know exactly how to play you both for what they want. Guaranteed. I don't care how unified a front you think you're putting up. It's not. Blood is always thicker than water.
It's also long term, worth figuring it out.
When we were grown and my step-sister called to say she'd been abused by husband number two (and that crap will also happen as a result of kids going through childhoods in dysfunctional relationships - they naturally return to what they know when nothing else works in adult life), it was a race between me and my stepdad as to who would be on the road first to drive many States away and make sure that jackass knew he was never ever going to touch her again.
He beat me there and apparently stood in the guy's house and said "She will pack up whatever she wants and we are loading it in the vehicle and leaving and you will not speak to her or even be in the same room as her while she does it."
It'll work out, but it's not going to be pretty. They're at a really difficult age for kids from broken homes and it really doesn't matter much at what age the divorce happened or anything. They're comparing themselves silently to "normal" families and they haven't learned yet that "normal" is just a setting on the clothes dryer. They're not old enough to get that yet.
It will help them if you as step dad talk to them about it by asking them questions. Simple questions. Leading questions. Help them think it through.
How do they feel about it? Do they think you like how it's going? Do they care? Do they know you love their mom? What do they think should be done? Is it realistic? Show them how those things would actually be worse with love and reality. 10 is a little young but 13 isn't for those discussions.
It'll take seemingly forever, but they'll slowly start to get it. And they'll still behave like brats when it serves their purposes and they know you're too tired to fight it.
Another thing that helped all of us kids was realizing there's folks a lot worse off than we were. My mom made sure we helped other families that were worse off whenever we found out about it and us kids were involved either with physical labor or via knowing the finance aspect of why we would be giving up some things to make sure someone else had a helping hand.
That drove home for all of us that even our dysfunctional little teenage angst ridden mess of a family still had it more together and were better off than the folks we helped.
Someone mentioned getting the kids to church. That can work or it can backfire, but generally the thing they're getting in most normal church congregations isn't only religion, it's seeing folks from all walks of life with all sorts of problems and even folks with seemingly no problems who all behave (hopefully) generously and who genuinely care about others.
A friend of mine who isn't particularly or heavily religious still took his kids to church regularly for the "resetting of their little moral compasses" aspect of it for many years. One of his kids decided on her own that being more religious than dad was for her. The other wasn't as interested, but appreciated and understood later what her folks were trying to do. The boys were somewhere in between.
They did a few Habitat for Humanity trips instead of vacations and basically gave all four kids things to think about bigger than their limited viewpoint wants and desires.
Other "shaping" things for me were things like time with my grandfolks. I know not all kids have that luxury nowadays, but spending a few summer months in an old couple's home of two tough old birds who weren't afraid of a little work and came of age during the Great Depression, really teaches modern spoiled kids a big lesson about the bigger picture. Having grandpa or a surrogate grandpa drag your little butt out of bed at the ass-crack of dawn all summer and working on the farm or at various chores from sunrise to sunset on weekdays, and seeing the old man looking like he never needs any sleep and gets twice the work done you do, is a good lesson for any kid. Got any family that lives on a farm? Those kids spend a summer working a farm, they won't have enough energy left to do anything wrong.
