Carlin will run ex-Formula 1 driver Felipe Nasr and Formula 2 race-winner Sergio Sette Camara in this week’s official IndyCar test at Austin.
Both drivers are expected to also be confirmed for the 2020 IndyCar season, rounding out this year’s full-time field.
The pair will join Max Chilton, who was confirmed for a road and street course and Indianapolis 500 programme with Carlin last week.
Both Brazilians are expected to share the team’s #31 entry, with details of how they will split the ride to be confirmed at a later date.
Neither driver has yet raced in IndyCar, although Nasr tested for what was then Schmidt Peterson Motorsport last summer.
Nasr is also no stranger to racing in the United States, having raced in the IMSA SportsCar Championship for the past two seasons – winning the 2018 title and last year’s Sebring 12 Hours.
He previously raced for Carlin during his championship winning British Formula 3 campaign in 2011 and then in GP2.
Sette Camara, another Carlin junior formula veteran, meanwhile moves over from F2 where he has competed for the last three years, taking a best finish of fourth in the points last year with two race wins.
He also served as an F1 test and development driver for Toro Rosso in 2016 and McLaren last year.
Nasr will drive on day one of this week’s test on Tuesday before handing over to Sette Camara for Wednesday. Chilton will be in action on both days.