The former NRL star shared an intimate video of Lee changing the new bub's nappy, joking that they didn't smell bad.
'Even Gigi's poo smells like flowers,' the 36-year-old wrote with a Pinocchio-face emoji.
Personal trainer Rachael looked relaxed and at ease with the new bub, as she already has a son from a previous relationship. Braith's mother Kim was also seen in the clip.
The former footballer, who shares three-year-old daughter Aleeia with ex-wife Jodi Gordon, also shared the adorable moment Aleeia met her new baby sister.
Congratulations to Braith and Rachael!