C.S.
Hi L.,
Have you tried limiting the things they can play with at any one time ? Maybe putting the other things in cubies or even milk crates up in a closet and as they want to play with those particular things bring them down one at a time ? (organize them by like things, dolls in one ,color books in another ,etc. even maybe adding some shelves in their rooms for books and other things )as they finish playing with them they go right back in the container they came out of before the next box is provided.
make them responsible for picking up after themselves and reward their daily cooperation by using a chart with stars, (for girls you could even buy some cheap silk flowers and give them one a day for each day they pick up after themselves and by the end of the week they'd have a real bouquote ! each time they get the 7 flowers,) reward them at the end of the week for such a great job! This would also include picking up their dirty clothes ,shoes, etc.) Consequences would be that they can't play with the things they refused to pick up when it comes to the toys, and so on. Maybe a reward at the end of the week could be a real special Tea Party (depending upon thier ages) painting thier fingers and toes for them, etc. Hope this at least gives you some ideas. C.