Your kids sound old enough for you to sit down and speak to them calmly about the things that are on your mind. Let them know that you understand they're frustrated with the changes in their lives, but what you're doing now is for the benefit of all and you're tired.

I don't know what to do about the bickering with siblings, my kids still do that two of them are adults. But I don't have to hear it. When they start, I tell them to solve the problem quietly, get over the small stuff.

Let your oldest know that he/she is a role model for the younger children and expect him to behave accordingly. For roughhousing, if they're messing around in the livingroom, they're not allowed in there until they can behave. Back talk I would send them to their room until they were willing to express themselves in a respectful way. Most kids are messy and don't really like cleaning up after themselves, but it's a fact of life. If they're not following your rules, take away computer, video game, and TV. Another thing that was very effective with my kids was if they did not empty the dishwasher when it was their turn, then that chore was theirs for a week. If they didn't put their clothes in the hamper, I taught them how to do laundry and that chore was theirs for a week. (I'd recommend jeans or towels only until their skills improve.)

Is there any way that you can talk to their dad and have him get on board? Even though the two of you don't get along, they are his children and certainly he'd like them to behave properly.

Make sure that you are praising them when they are behaving. Younger kids in particular go out of their way to seek that approval.

I would also suggest an evening or afternoon (weekend) a week that you all do something together. Attendance is required by everyone. Play board games, cards or watch movie. Sometimes we get so busy with our lives that we forget that quality time kids need. Make a simple meal that everyone eats together use paper plates to make clean up easier and that evening is family time.

Your idea to pick your battles is a good one. If the kids think you're going to be frustrated no matter what, they're not going to try. If you feel yourself getting frustrated go in your room, or take a bath.