S.M.
It sounds to me like they have far too much time on their hands and are unsupervised too often. You need to go back to the basics. They sit where you say, play what you say, put things away when you say, don't eat until they clean up, one activity at a time, give them two choices for activities if possible, but then YOU DECIDE from the time they get up to the time they go to bed what happens every minute. If they don't listen they lay down with books and are only allowed quiet time activities. TALK to them every minute of the day telling them how things will be, where you are going next etc. Every day they push the limits, they go to bed earlier. Tell them you are so tired from having to deal with their behavior that you need the time alone. You just need to be the alpha female and take charge.