Four heart-shaped foil balloons flutter high along the golf course's fence; three pink, one blue - one each for the four children who died there on Saturday night allegedly at the hands of an drunk driver.

Siblings Antony Abdallah, 13, Angelina, 12, and Sienna, 9, and cousin Veronique Sakr, 11, were walking and bike riding with three other children down Oatlands' Bettington Road just before 8pm.

Leila Abdallah at the scene where three of her six children were killed by an alleged drunk-driver. Credit:Edwina Pickles

As they made their way down the street's gentle slope, Samuel Davidson was driving from the opposite direction.

On his way home from a party after what police will allege in court was a day of drinking, the 29-year-old allegedly ran a red light at the street's intersection with busy Pennant Hills Road.