For the past few weeks the beloved presenter has been enjoying a well-deserved break with her mini-me daughter in Fiji.
And as the new issue of Woman's Day reveals, Grant, 53, secretly flew into the country to spend five blissful days with the pair.
"He had a great time in Fiji with the two of them, and it was very daring of him to throw caution to the wind and just do it, because Grant is just not like that," a source explains.
Fifi, 39, took to social media to post a candid holiday snap of daughter Trixie jumping into the arms of her dad during their family holiday.
"Leap of faith with no floaties!" Fifi mused alongside the image.
Although the mother-of-one didn’t name Grant in the caption, it didn’t take long for eagle-eyed fans to point out the similarities.
“With her dad, precious,” one used remarked. “And into Dads arms, How AWESOME! Onya Grant,” another penned.
In April The Project beauty, who has always remained silent on who Trixie’s father is, finally addressed the matter in a series of telling photos featuring her darling daughter playing with her dad at her third birthday party.
"Bouncing castle daddy cuddles," Fifi mused.
Fifi and Grant secretly dated in 2012 but broke up just before she revealed she was pregnant with her first child.
The pair have never commented on their tryst. Trixie is often spotted with her look-alike half-siblings Jamie, 26, Morgan, 23 and Jett, 19, who Grant shares with former wife Lisa Curry.
Meanwhile, it hasn’t just been pool-side shenanigans during Fifi and Gran'ts escape.
The radio presenter has also taken Trixie along to volunteer at a local school. In a particularly cute Instagram snap, the blonde tot sits at a desk with a group of students covering her eyes.
“This is Trixie letting me know she has no interest in ever going to school,” Fifi joked.
To find out more details on Fifi and Grant's secret Fijian holiday and their plans for the future, be sure to pick up the latest issue of Woman's Day, on stands now!