Fortunately for us, they captured the moment on video, which Rowland posted on Instagram Tuesday.
As the duo harmonized, baby Titan could be seen bouncing on Williams' lap and beaming up at his mama.
"Ok your turn, add a third, post the video and make sure you hashtag #TITANSsong #GO," Rowland captioned the video, encouraging fans to add to the melody.
Rowland has also spent time with her other BFF, Beyonce, since welcoming her first child with husband Tim Weatherspoon last November.
"Just the other day we were all able to sit down and have lunch together, and that always feels good," Rowland said, while joking that it wasn't all girlfriend time. "Titan’s screaming and Blue is probably climbing something," she told host Meredith Vieira.