Jennifer Lawrence has denied she'll have any sort of cameo in The Hunger Games: The Ballad of Songbirds & Snakes.
Speaking on Watch What Happens Live, Lawrence was asked about her involvement with the prequel, and if she'd be playing Katniss' grandmother. "Oh, 'cause I'm 49 in Hollywood years, huh?" Lawrence remarked. "No, that's not true."
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The Ballad of Songbirds & Snakes takes place 64 years before the first movie, so we definitely wouldn't see Katniss or any of the original cast, besides a young President Snow, whom the movie is centred on.
Still, Jennifer Lawrence isn't necessarily done with The Hunger Games, as she's said in previous interviews that she'd love to return to the role of Katniss.