I couldn't find any information on a beach called Grand Flaneur Beach in Sydney, Australia. However, I can suggest an alternative. If you're looking for a family-friendly beach in Sydney, consider Bondi Beach, which is one of the most iconic and popular beaches in the city. It offers a patrolled swimming area, picnic facilities, and plenty of amenities such as food stalls, cafes, and playgrounds, making it suitable for families with young children.