Joaquin, 49, and Mara already are parents to son River -- who was born in 2020 and is named after Joaquin's older brother, actor River Phoenix, who died at the age of 23 from an overdose in 1993.

She shares a son with her fiancé, actor Joaquin Phoenix. Kate Mara Steps Out with Husband Jamie Bell and Sister Rooney Mara at L.A. Fundraiser for Chimpanzee Rescue Watch Joaquin Phoenix Sweetly ...