I don't know where to start so I'll start by saying I am a step granddaughter, a step daughter, a step sister and a step mother. 
I treat my step kids the same way I was treated. (my stepdad was very good to me) 
I met my husband in 2001 through a friend. we were both in relationships at the time. His GF already had a son, who my husband had taken in as his own. He had two more kids with his ex, I didn't have kids with mine. In 2007 we got together & 2008 we were married. He moved into my house. At the time the kids (all 3 boys) were 3, 5, & 7. They were dirty, mouthy, undisciplined hoodlums. At first I didn't want to get involved with disciplining his kids, I thought It wasn't my place, I would sit & watch as they jumped on my furniture til the springs were sticking out, they colored my walls, They slammed my doors until they no longer shut, I would find gum stuck to my furniture, carpet & walls. I would wait for my husband to do something but he just ignored their behavior. Then one day the 5 year old (now 9) grabbed his crotch & yelled at his dad "suck my d**k, b***h" My husband just laughed, & recorded it all on the camera. That was it for me. From then on I took charge. I was pregnant with my first son at the time & the way these boys were acting they weren't going to be anywhere near my son. The boys learned real fast I wasn't going to put up with their BS. However it did cause problems between me & my husband. I had to kick him out a few times but with no where to go he had a few options, go back to his ex, be homeless, or live with my rules. He always came back. The boys were slowly getting better. Unfortunately, my first son was stillborn at 39 weeks my husband & I feel into a depression & the boys took over again. everything I taught them was gone. It wasn't long til I got pregnant with my second son but due to bed rest I wasn't able to take back control of my house. All I could do was listen from another room as they tore up my house. Until I got off bed rest. It took a lot of yelling, lot of fights, lots of "get out of my house" but not only is my husband a better father, the 9 year old is almost the perfect child. He now bathes, brushes his teeth, very polite, very sweet, he does chores, and is a very good & protective brother to my 2 year old. 
(sorry my story is so long) here are my problems. The other two are more like their mother. They don't listen, they are lazy, don't do anything & they don't care. The oldest one is 12, he poops his pants & just sits in it. His mother says its a medical condition. Fine, whatever. I bought him night time pull ups for older kids. They're suppose to look like real underwear. Instead of wearing those he wears his brothers underwear so he don't mess up his. He is suppose to clean any soiled underwear himself, but I don't want poop everywhere so he has to clean them in the toilet before they go in my washer. To retaliate against having to clean his mess, he found broken glass, took it to my 2 year olds room & stuck it in my sons mouth trying to get him to eat it. There are cameras in my sons room, we can see & hear everything that goes on it there. He refuses to come back after that because his father spanked him & his mother lets him do whatever he wants. 
My biggest problem is the (almost) 7 year old. He acts like he is 3 & strangers think he is 5. Just when I think I'm starting to get through to him it's time for them to go back to their mother, who then sends me messages about how bad he is being. (She can't control him and uses me as a threat) I get messages saying he is throwing rocks at cars as they drive by, he tore the head off a little girls doll, he's shoplifting, he called a little girl a b***h, he lifted up a little girls dress & pulled down her underwear. *sigh* we have the boys whenever they don't have school, every weekend, summer break, fall break, winter break, & spring break, every teacher conference. That's 190 days. My husband works nights and sleeps days, so basically I have the boys 190 days. When with us my (almost) 7 year old step son torments my cats, bullies my dogs, he breaks everyone's stuff, colors on everything, pees on the carpet, takes his poop out of the toilet & smears it all over the floors, walls & everything else, he has punched my 2 year old in the nose, taken his favorite toys from him & hides or breaks them, never listens, lies, does whatever he wants, he picks up ticks & throws them on his brothers, he does nothing but whine & cry when he has to do something he don't want to do. His brother has to pick out his clothes for him or he will wear clothes that are dirty, & inappropriate for the weather. (like 100 outside & dressed for snow) I'm really starting to dislike this kid. Today, we were outside playing & the kids have a wooden play set, clubhouse on top with a slide. I'm 5'5 & the floor of this clubhouse comes up to my eyes. My 2 year old was up there playing with my 9 year old stepson. The 9 year old went down the slide & was waiting at the bottom for his brother when the 7 year old went up, picked up my son & tried throwing him off the clubhouse. Thank God the good one was right there, i was only a few feet away in a chair but I'm 36 weeks pregnant & I think that's the fastest my pregnant butt has ever moved. But, I don't know what do about this kid. I have tried everything. His mother expects me to do everything, his dad sleeps most the day to work nights, even though the 9 year old is very helpful, how am I going to take care of a newborn, a 2 year old & a 7 year old that acts like a 3 year old?
I am also the sole provider for my step kids. Their dad don't get paid well but it's the best he can get due to some mistakes he made when he was younger & their mom don't work, lives off food stamps, state housing & child support, that she uses for herself. The first child support check she used to get herself a new tattoo.  I buy the kids birthday Easter & christmas presents, their school supplies, their clothes, shoes, Halloween costumes, winter coats, boots & hats, anything they need. she sends me a message whenever they need something. but they still show up dressed in rags inappropriate for the weather. She dropped them off once in the middle of a blizzard none of them had their coats & one was in shorts. Then she takes off to another state with strangers when the kids are suppose to go back to her for school. We live an hour away from their school. The 9 year old wants to stay with us & gets upset when it's time to go to his mom, the other two want to stay with her because they don't like discipline or chores. The kids have been in & out of homeless shelters & are currently living in a horrible neighborhood surrounded by gang shootings & drug dealers. She lets people smoke & drink in her apartment & move in & take over the kids room kicking them out onto the couch. These people have also stolen the kids tv & video game consoles, but she don't care. They have changed schools 5 times in the past 4 years. They are always starving when they come over because their mom uses their food stamp to buy other people food so they never have anything to ear. Child services has visited them a few times but they never do anything. Their father & I live in a quiet, small town where there is very little crime, friendly people, everyone knows everyone & you grow up with the same kids. A way better place for the boys. We can't talk their mother into moving to our town & she won't let them live with us. She don't want to pay child support even though we never asked her to, its not about the money, its about the kids. Now even though they share custody my husband plans on signing our 9 year old up in our small town school after summer vacation. Would my husband get in trouble for violating the custody agreement since she is suppose to have them for school?