This is the ACO press release and I would think they know for sure. Plenty of brothers and father and sons, but no other father and 2 sons.
I would like to compliment the paper or their extensive piece, and look forward to reading more, along with a full review once the dust has settled.
A great family story
Entrants have until 12th May to announce their driver line-ups. One trio is already known. It is not only a great family story but also a first in the race's history!
The driver line-up in question consists of a father and his two sons. The dad? 56-year-old Nigel Mansell, the 1992 Formula 1 World Champion: the sons? 22-year-old Greg and 25-year-old Leo. Only Leo has raced at Le Mans before, in 2009 in the Team Modena Ferrari (27th overall).
This 100% family team made up of a father and his two sons is a first in the long history of the Le Mans 24 Hours. In the era, when 2-driver teams were the norm, there were father and son duos, the most famous being the Rosier family in 1950, with Louis and his son Jean-Louis, who won the race outright in a Talbot. In 1982, Mario and his son Michael could have repeated the same feat but their car was disqualified with a few minutes to go to the start because of non-compliance with the regs. In 1988, there was a 100% Andretti trio at the start when Mario and Michael teamed up with Mario's nephew John. Among other family references are: 3rd place for Derek Bell and his son Justin in 1995 in a McLaren (Wallace was the 3rd driver), Felbermayr father and son in 2007 in a Porsche, Jean-Louis Ricci and his son Romano in 2000 in a Porsche, John Paul Jr and John Paul Sr in a Porsche in 1980. And in 1979, American brothers, Bill and Don Wittington with Klaus Ludwig achieved a fabulous outright victory, without forgetting the Mexican brothers, Pedro and Ricardo Rodriguez, in the 60s