It has been a long wait for the next "The Princess Diaries" movie, but author Meg Cabot revealed the script for a potential third installment has already been completed.

In a recent interview with Entertainment Weekly, Cabot alluded to the possibility of a third installment of the popular franchise, which could likely be done as a tribute to the late director, Garry Marshall.

"I am not allowed to say," the 50-year-old award-winning author said when asked about potential plot lines. "I would love to sit and talk about [it], but I can't. I'm not allowed. But it's really more following the movie than the books, so if she — the last version I read, she definitely did not find out that she has a biracial younger sister ... which I personally would've thought was hilarious, but that was not the direction they were going."

"The Princess Diaries 2: Royal Engagement" ended with Princess Mia (Anne Hathway) crowned as Her Majesty Amelia Mignonette Thermopolis Renaldi, Queen of Genovia with her grandmother, Queen Clarisse Renaldi (Julie Andrews), and best friend, Lilly Moscovitz (Heather Matarazzo), in attendance at the royal palace. An epilogue then showed that the Genovian Parliament now allowed female members.

Should Walt Disney Pictures decide to move forward with "The Princess Diaries" sequel, which original cast members are coming back for round three?

In a past interview, Hathaway and Andrews said they were open to reprising their respective roles in a possible sequel.

Mandy Moore, who starred as Lana Thomas in the first installment, said she would be down for a cameo as well. In particular, she wants her character to make amends with Mia and apologize for being a bully when she was younger.

"If I'm going to be involved, I would be down for a cameo," Moore, 33, shared with Elle. "I would like to see this woman [Lana] evolve."