Dee Devlin's sister jetted off to France on a private plane to attend Conor McGregor Jr's fifth birthday party.
The UFC star's son turned five on Thursday and celebrated with a party over the weekend in southern France.
Cathy Devlin shared snaps on her Instagram story as she boarded a private jet with her husband Ross Sargent and their five-month-old baby son at Dublin Airport.
She also shared a video of Dee helping Conor Jr to blow out the candles on his birthday cake at the party on Saturday.
It comes after former two-weight champion McGregor took to social media to wish his oldest son a happy birthday.
He shared a number of snaps on Instagram as he paid tribute to Conor Jr.
Commenting on the post, McGregor said: "My boy is 5!!"
In the photos, McGregor and Dee could be seen smiling alongside Conor Jr and their other two children, Croia and Rian.
The Notorious and his family went to a restaurant, with Conor Jr getting a spiderman decorated cake.
Former Republic of Ireland footballer Robbie Keane and McGregor's coaches John Kavanagh and Owen Roddy were among those to also send birthday wishes to the youngster.
UFC star McGregor is currently on holiday with Dee and their three children in southern France after picking up his new €3.5million Lamborghini yacht earlier this week.
He posted on Instagram after getting the luxury boat: "Today is the day!! We officially take ownership of our brand new Lamborghini Sport Yacht! But first.. the most important meal of the day."
McGregor later posted an image of himself driving the yacht alongside a video, captioned: "Trying to find the words. The supercar of the sea!"
The luxury yacht is known as "the supercar of the sea" and is 63 feet long while capable of producing 2000hp.
With a green hull, the luxury sea-liner pays homage to his whiskey brand Proper Twelve, which he sold in April last year for around $150m. Its luxury interior also catches the eye, and he has secured the Number 12 edition of the yacht in another tribute to his business.
His latest purchase joins a whole host of opulent toys, which also includes a series of cars such as the Lamborghini Aventador Roadster and his Urus.
McGregor's parents Tony and Margaret are also in France, with his father getting behind the wheel on the yacht last week.
Meanwhile, McGregor is on target to achieve his goal of becoming a billionaire before he is 35, an expert has predicted.
Leading US sports analyst Andrew Petcash claims the fighter will beat his own ambition by at least a year based on current earnings.
McGregor, 33, told ESPN in 2020 he would be a billionaire by the time he was 35.
But now it looks like the Notorious is set to achieve it by the time he turns 34 in July.
Sports entrepreneur Petcash, who compiles online sports newsletter the Petcash Post, posted his McGregor forecast on Twitter.
He tweeted: “Conor McGregor will be a [dollar] billionaire this year, (earning) $235m from fighting and a $600m deal off the ring.
“McGregor makes a lot from fighting. A study by OLBG found that he makes over $8m for every minute in the octagon.”
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