Alex Fontana will return to the GP3 Series with the Jenzer squad at the Hungaroring this weekend.
The Swiss driver is currently racing in Formula 2 and lies ninth in the standings following last weekend's Paul Ricard double-header.
But he is returning to the team with which he made his GP3 debut at Spa last year, taking the seat in the third car that has not been used since Facu Regalia raced it at Silverstone earlier this month.
Regalia, meanwhile, has joined Atech CRS for the Hungaroring event after missing the Hockenheim round last weekend to concentrate on his Auto GP commitments at Curitiba.
Like Jenzer, Atech also ran just two cars at Hockenheim, but will field three in Hungary with Argentinian driver Regalia joining regulars Tamas Pal Kiss and Ethan Ringel.
The announcements mean that Trident is the only team in the field not running all three cars in Hungary.