During an episode of Star Wars News Net’s The Resistance Broadcast, ABC News’ Clayton Sandell revealed that he had spoken recently with Fisher’s brother, Todd Fisher, about all of this. Per Sandell, Fisher confirmed that Abrams and company would be using unused Last Jedi footage as well:
“I talked to Todd Fisher today about all of this and he has been talking with J. J. Abrams about it. I asked him, because the press release only said The Force Awakens so I asked about The Last Jedi, and they are also using unused footage from The Last Jedi. I asked him how many minutes of footage they had from it and he said ‘I can’t tell you that!’”
Read more at /Film.