"It was a poignant thing, and something that nobody took lightly - that she was willing to stand in for her mom," says ILM Visual Effects Supervisor Patrick Tubach.
J.J. Abrams had promised that they would not recast the role of Princess Leia for "The Rise of Skywalker" after Carrie Fisher's untimely death, nor would they digitally recreate her for the final chapter of the "Star Wars" sequel trilogy.
But as it turns out, they did a bit of both for one crucial scene that simply couldn't be created from scrapped footage of Fisher's performance in "The Force Awakens" and "The Last Jedi." Most of her scenes were repurposed from those earlier performances, but it simply wasn't going to be possible to use anything they had to create a flashback scene set shortly after "Return of the Jedi."
In the scene, Luke Skywalker is shown training his sister in the force, which is an important detail to add credibility to Leia taking over the training of Rey for this latest episode.
They were able to use de-aging technology on Mark Hamill, so he could reprise his own role as Luke. But when it came time for Leia, Abrams decided to honor Fisher's importance to the franchise by offering the role to her daughter, Billie Lourd. She was already on-set with her role as a resistance leader throughout the trilogy.
"Billie was playing her mother," ILM visual effects supervisor Patrick Tubach told Yahoo "It was a poignant thing, and something that nobody took lightly -- that she was willing to stand in for her mom."
According to Tubach, seeing Billie dressed as Leia was "an emotional thing for everybody." He went on to add, "If you're going to have someone play [Fisher's] part, it's great that it's [Billie] because there are a lot of similarities between them that we were able to draw from."
But as much as Billie resembles her mother, she also has her own distinct and well-known look, so producers opted to digitally replace her face with Fisher's, but they needed Fisher as she looked in the mid-1980s. Luckily, there was scrapped footage from "Return of the Jedi" as well they had access to, and thus Billie Lourd's transformation into Princess Leia was complete.
"The idea was to provide this great surprise where they take the helmets off, and you see Luke and Leia's younger faces," said visual effects supervisor Roger Guyett.
It certainly worked out that way, and if fans want to be upset that they dared recast Leia (sort of) after saying they wouldn't, it's at least an easier pill to swallow if you know that it was not only done with the blessing of her family, but it was her own daughter paying homage to Carrie Fisher's most iconic role of all time.