Fonda and Tomlin play long-time rivals who form a bond when their husbands declare their love for each other, according to The Hollywood Reporter.
The spouses of Fonda and Tomlin's characters will be portrayed by Martin Sheen and Sam Waterston.
Raphael has now been cast as the daughter of Grace (Fonda) and Robert (Sheen)
'Grace and Frankie' has been created by Marta Kauffman (Friends) and Howard J Morris (Sullivan & Son).
The series is expected to debut on Netflix in 2015.