A spokesman said the decision "reaffirms the family's commitment, for the present and the future to the whole Atlantia group."
The operator has grappled with the aftermath of the deadly collapse in August 2018 of a motorway bridge in Genoa and questions have been raised over the family strategy following the death last year of Gilberto and Carlo Benetton, two of four founding members of an empire stretching from the eponymous clothing label to catering group Autogrill.
On Thursday, Atlantia said it had appointed Gilberto's daughter, Sabrina, as non-executive director.
At the same time, Aeroporti di Roma, the company controlled by Atlantia that runs Rome's two airports, appointed Carlo's son, Christian, as non-executive director.
Atlantia's electronic payments business Telepass appointed Franca Bertagnin Benetton, as non-executive director of its board. She is the daughter of Giuliana, sister of Gilberto, Carlo and Luciano, the fourth member of the founder generation.
The appointment of the three Benettons to the Atlantia units provided an outward sign of the family's engagement with the business, which has been under pressure since the Genoa disaster in which 43 people died when a bridge it operated collapsed.
But it left unclear the wider issue of how the family intends to manage their Edizione holding company, which controls its portfolio of industrial stakes.
Gilberto, co-founder of retailer United Colors of Benetton, was the mastermind behind the family empire's diversification into construction, transport and catering.
Earlier this year, Edizione appointed veteran manager Gianni Mion, for years the right-hand man of Gilberto Benetton, as chairman of the group's new board.
(Reporting by Francesca Landini and Stefano Bernabei, writing by Giulia Segreti; editing by Grant McCool)
