Hi. I don't know how old your girls are but I would maybe suggest a system that works for you. Here are some options: 1) tell the girls that if they want to play in their own doll house they can do chores and earn money to buy their own. You can give them 50 cents for drying the dishes, whatever. If they are motivated enough this will work or else they'll learn to be content with what they have. 2) same as #1 but maybe two girls can go in on it together then it's theirs to share. 3) Tell them that you can sell the dollhouse and divide the profits 4 ways. 4)-this works at our house by the way - tell each girl they have "Their Special Day" once a week where they get to play with the house alone. Each girl gets a special day once a week, so it's fair. The other 3 days are days off the doll house. 5) Same as above, but instead of playing alone they just get to play first, for a designated amount of time, like 15 minutes, then the other 3 can join in. GOOD LUCK!
BTW, At our house we have 3 kids who are 8,6,and 5 and each one has 2 "Special Days" per week where they get to be first to pick whatever - the seat in the car, the TV program, the seat for dinner, etc. They are also first in the shower (they hate that) but it is good for them to understand equality. Everybody gets to be first on their own day and they know when their day is. At our house kids are only allowed on the computer or gameboy on their day, for 20 minutes. It has really cut down on the arguments.