Michele Beretta and Konstantin Tereshchenko will join the ranks of the GP3 grid at Sochi, partnering with Trident and Campos respectively.
Beretta, 20, races in the European Formula 3 series and is currently contesting his second season in the championship, representing Mucke Motorsport.
The Italian was the 2013 Formula Abarth runner-up but has yet to score points in F3.
Meanwhile, Russian racer Tereshchenko, 21, is a title contender in his sophomore Euroformula Open campaign, with four wins to his name.
He has been racing with Campos in EF Open since 2014 and was entered into the GP3 round at Spa in 2014, but was sidelined before the races by a massive crash, having launched off the kerbs at Bus Stop during practice and his car subsequently catching fire.
Beretta will be replacing Amaury Bonduel at Trident, while Tereshchenko takes over for erstwhile Prema F3 pilot Brandon Maisano at Campos.