The star's brother, Todd Fisher, confirmed in an interview with the New York Daily News that Carrie will appear as Princess Leia in the new movie without the use of CGI.
"Both of us were like, 'Yes, how do you take her out of it?' And the answer is you don't," Todd said of the decision, which he made with Carrie's daughter, Billie Lourd.
"She's as much a part of it as anything and I think her presence now is even more powerful than it was," he explained. "I think the legacy should continue."
Carrie played Leia in Star Wars (1977), The Empire Strikes Back (1980) and Return of the Jedi (1983), and reprised the role in The Force Awakens (2015). Episode IX will use recent footage of the actress, although the extent of her presence is unknown.
"I'm not the only part in that equation, but I think the people deserve to have her," Todd said. "She's owned by them."
"You don't mess with this legacy," he added. "It would be like rewriting the Bible. To me, Star Wars is the holy grail of storytelling and lore and you can't mess with that."
Carrie died of a heart attack at age 60 on Dec. 27, and her mom, actress Debbie Reynolds, died the next day. Carrie finished filming Star Wars: Episode VIII prior to her death, as co-star Daisy Ridley announced in July.
"And that is a wrap on Star Wars: Episode VIII. My heart is brimming. #reyout," the actress wrote.
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