Canadian Lance Stroll has secured a testing role with Williams next year, BBC Sport has learned.
The 17-year-old, whose father Lawrence is one of the world's richest men, raced in Formula 3 this year.
Sources close to the team say Stroll's role will be separate from that of Williams' reserve driver, whose job is to provide cover for the race drivers.
Briton Alex Lynn, Williams' development driver this year, is a contender to replace Adrian Sutil as reserve.
A Williams spokeswoman said the team could not comment on Stroll's appointment.
The team are retaining Brazilian Felipe Massa and Finn Valtteri Bottas for a third season as team-mates in 2016.
Test driver Susie Wolff announced last week that she was retiring from racing at the end of this month.
Stroll's position and title - which is likely to be either test driver or development driver - are to be confirmed later this month.
His role with Williams is expected to involve plenty of mileage in older cars that are not covered by F1's in-season testing restrictions. He is likely also to drive the team's simulator.
Any driving at official tests in the latest car would, initially at least, be done by Massa and Bottas or the reserve driver.
Lawrence Stroll is to make a significant financial contribution to Williams in return for his son's position.
The 56-year-old, who made his fortune in retail, is said by Forbes to be worth $2.4bn (£1.58bn) and to be the 16th richest man in Canada. He has been keeping an eye out for ways to promote his son's career towards F1.
But Stroll Sr is understood not to be taking a shareholding in the Williams team at this stage.
His son has shown promise in European F3 this year, finishing fifth in the championship in his first season in the category, although he was also hit with a one-race ban for causing a multi-car crash in one of the races.
He is to continue in European F3 with the Prema Powerteam in 2016.