Posting to her Instagram story yesterday, Lisa shared a sweet snap of Grant with his two grandsons, Flynn, two, and Taj, two-months. The adorable young'uns are the sons of Lisa and Grant's daughter Morgan and her husband Ryan Gruell.
"Pa and his grandsons," the former Olympian captioned the sweet image.
Lisa and Grant reunited for Australia Day and the 58-year-old took to her Instagram account to share another pic of her ex with the newest addition to the family.
In the snap, little Taj is snuggling up to Grant on a brown lounge while the grandfather looks at the bub adoringly.
Lisa has previously opened up about how she and Grant manage to co-parent and grandparent with such ease.
Speaking exclusively to Now To Love in 2020, the 15-time gold medallist confessed it was the actions of her own father who inspired the swimmer to mark each occasion as an entire family - exes and all.
"My dad didn't see a lot of my career firsthand, to me at the time it didn't really bother me too much," Lisa explained.
"But, when you look back at it, you think, 'Oh gee, it would have been nice for him to share in those successes.'
"I think because of that though, Grant and I as parents, we always said we will always be there for all our kids, for everything that they do.
"Every success, every failure, every try, everything it didn't matter. Just being there and being proud is really important as parents."
Lisa and Grant married in 1986 and had three children together, Jett, Jaimi Lee and Morgan. Jaimi tragically passed away at age 33 due to long-term health complications.
Lisa is now married to Elvis impersonator Mark Tabone and Grant is reportedly single after splitting from TV and radio presenter Fifi Box back in 2012, right before she gave birth to their daughter Trixie, 7.
Grant has also been pictured celebrating some of Trixie's milestones along with Fifi, proving he is used to co-parenting without any dramas.