Liam Payne and Louis Tomlinson have recorded dialogue for a scene where 1D gather round a campfire with Stewie and Simon Cowell.
"There are not a lot of shows that, in the same season, feature guest-star appearances by both Frank Sinatra Jr and One Direction," producers Richard Appel and Steve Callaghan told Entertainment Weekly
"And we really enjoyed their time with us, until we realised we were both old enough to be their fathers."
This episode – titled 'Run, Chris, Run' – is expected to premiere on Fox in the US in May.
One Direction are joining an impressive set of Family Guy musical guest stars, including Adam Levine, Paula Abdul and KISS.