Brothers Kyle and James Smith from the Vale of Glamorgan were both travelling in the same car which crashed in 2005.
Kyle was 16, not wearing a seatbelt, thrown from the vehicle and died.
James was 15, wearing a seatbelt and survived.
Their mother Angie Smith says she has "no doubt" that she would have lost both boys, had James not been wearing a seatbelt.
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Breezy overnight. It will become fairly cloudy as the night progresses.
It should turn cloudier through the early hours with some patchy drizzle and some hill fog too.
It will be a breezy day with variable amounts of cloud and some bright or sunny spells.