Virgin Racing Formula E driver Bird will line up alongside Davide Rigon and Miguel Molina in Ferrari's #71 car for both races after losing his full-season WEC drive for 2019/20 as a result of the number of potential date conflicts with FE.
The postponement of the clashing Sanya FE race in China due to the ongoing coronavirus crisis clears the way for the Englishman to race at Sebring as well as Le Mans.
Ferrari GT racing boss Antonello Coletta told Motorsport.com: "Sam is part of our family and an official Ferrari driver, but [now] in a different mode.
"For the moment we have Sam just for Sebring and Le Mans, but the agreement is open to other races, respecting his FE contract."
He stressed that it was too early to talk about whether Bird could race full-time in the 2020/21 WEC and said that no decisions will be made about drivers until the summer.
Coletta added that Bird's return to the Ferrari WEC squad was unrelated to the disappearance of the last remaining WEC/FE clash after the postponement of the Sanya E-Prix.
He said that it was Ferrari's original intention to run just Rigon and Molina in the #71 entry at the Sebring WEC race on March 20 prior to Bird joining them at Le Mans.
Bird is part of an unchanged line-up in the two GTE Pro AF Corse-run Ferraris for the WEC season finale at Le Mans on June 13/14.
James Calado and Alessandro Pier Guidi, the regulars in the #51 entry, will again be partnered by Daniel Serra as they defend their GTE Pro crown at the French enduro.
Serra will also race at Sebring alongside Calado and Pier Guidi, making Ferrari the only GTE Pro manufacturer to opt for three-driver line-ups for the Florida race this year.