Me and my girlfriend have been together for almost a year, she hadn't been long come out of a 13 yr relationship the father of her 4 kids. They are a 12 yr old son, 11 yr old son, 6 yr old daughter and a 4 year old son and I have a 9 yr old daughter. The father has quit having anything to do with them since I came around so we have them 95% of the time, my daughter comes every other weekend. The problem I have is there is absolutely no structure and most of the time no consequences for there behavior. This has been an ongoing issue since day 1 between me, her and the kids.

Im currently working on this situation and it was going good but starting to spiral back out of control, all of the kids get food and drinks and will take them in there rooms, in the living room, in our room when I'm at work (she works at home). Well it started really bothering me because there would be food and drink spilled all in the couch, in the floor of there rooms, in the beds so I finally said something because my girlfriend would run herself ragged every afternoon trying to clean up the house. During the summer when the kids were home and she was having to work and try to watch them she told me that she couldn't watch every little move they made, I get that but I'm like why don't we start making it a habit for them to sit at the dining room table to eat and drink when they want food. She finally started staying on them about it and things we're getting better but that was short lived. Another thing is they eat what they want to, when they want to. When they home from school they start eating and will eat all the way up to supper time if we're at the house. Most of the time they eat a few bites of supper and done, then shortly after they'll go back in there for chips, snacks, etc.             Just the other night I came home from work and we were getting ready to eat supper that she cooked and ss4 and sd6 said they wanted a fruit roll up, I said let's eat supper first and you can have one. Well we started to eat and he didn't take 1 bite and said I'm done so can I have a fruit roll up and the momma said you need to eat supper so you grow and be strong well he keeps on like they all do and she gives one! I said why, she said I'm trying to get him to eat supper, well when sd6 seen that she had to have one so momma took her one and said eat supper first and then eat your candy. Next thing you know she's eating the fruit roll up and didn't eat but a few bites of her supper. I said something to her after supper and she said that there only going to be little once so if they want to eat Reese's for supper then that's what they can do! They can be disrespectful or acting out and she will tell them that she's going to do such and such as far as a consequence and never ever does it. If they ask for something and we don't answer right away they keep on on repeating it or say if we do say no not right now they don't accept that, they will keep on. So many times if she tells them not to do something I'll turn around and they'll be doing it, when I say something to her she says life's to short to worry about every little thing and that she's not going to be a drill Sargent mom. When I bring up them being disrespectful or not listening or caring what I say she says that I have to earn there respect before they will respect me. I just don't understand it, I was raised totally different. It really gets the best of me and upsets me because I feel like I'm fighting a losing battle and it's always my fault or why can't I be patient. My daughter is not perfect but I would never ever let her disrespect my girlfriend or not listen to her the way her kids do me. I really fell in love with this girl and other than the kid issues we don't have any problems but this is really bothering me because I really don't know if this is me trying to be to strict or there is a discipline issue here. 
I'm not the only one that says things, some of her family says things about them as well and she jumps down there throat about it. I've been in previous relationships and they've all had children and I've never had issues to this extent. Can someone please shed light on this situation or steer me in the right direction please? Thanks