AN ONCOMING DRIVER FAILED TO YIELD TO ONCOMING TRAFFIC (ME) BEFORE TURNING LEFT. WE NARROWLY AVOIDED AN ACCIDENT, BUT WHEN I BRAKED HARD AND SWERVED, BOTH OF THE SEAT BELTS IN THE THIRD ROW HOLDING MY CHILDREN'S CAR SEATS CAME UNDONE. (BOTH CHILDREN STILL USE THE FIVE-POINT HARNESS WHILE IN THEIR SEATS.) ONE CHILD (STILL STRAPPED INTO HER CAR SEAT) FLEW INTO THE BACK OF THE FRONT PASSENGER SEAT AND THE OTHER CHILD (ALSO STILL STRAPPED INTO HER CAR SEAT) FLEW INTO THE BACK OF THE MIDDLE ROW SEAT DIRECTLY IN FRONT OF HER.