Former West Wing star Schiff will play the father of Reagan (Christina Applegate), according to Entertainment Weekly.
A psychologist, Reagan's father will lend a helping hand to his daughter and her husband Chris (Will Arnett).
Schiff is best known for playing Toby Ziegler on The West Wing between 1999 and 2006. His recent credits include recurring roles on short-lived NBC superhero drama The Cape and axed CBS crime spinoff Criminal Minds: Suspect Behaviour
Meanwhile, Deadline reports that Danner will appear on Up All Night as Reagan's mother.
Danner - the mother of actress Gwyneth Paltrow - recently starred in the Meet The Parents film series and also played a recurring role on NBC's Will & Grace between 2001 and 2006.
The most recent episode of Up All Night drew just over 6m viewers for NBC, down on the 10.95m who watched the series premiere.
The show continues on Wednesday at 8/7c.
> Jorma Taccone to guest in 'Up All Night'
Watch a preview for Up All Night below: