Rod Stewart poses with 4 mothers of his children: 'A mothers' reunion!'

Some guys have all the luck.

On the occasion of his daughter Kimberly's 40th birthday, rock legend dad Sir Rod Stewart posed with her mother Alana and three additional mothers of a handful more of his children.

Kelly Emberg, Rod Stewart's fashion model girlfriend for most of the 1980s, posted the photo on her Instagram account.

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Emberg is the mother of Stewart's daughter, Ruby, who is also a model.

Rod Stewart and Kelly Emberg. (Photo by Ron Galella/Ron Galella Collection via Getty Images)

Rod Stewart and Kelly Emberg. (Photo by Ron Galella/Ron Galella Collection via Getty Images)

"Can’t believe you are 40!" she enthused to birthday girl Kimberly. "You looked radiant last night! #birthdaybash. A mother’s reunion!"

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In addition to Emberg and first wife Alana Stewart, fashion model Rachel Hunter --Stewart's second wife and the mother of two of Rod's children-- posed alongside Stewart's third and current wife, fashion model Penny Lancaster-Stewart, with whom he shares two sons.

Rod Stewart and Rachel Hunter. (Photo by Ron Galella/Ron Galella Collection via Getty Images)

Rod Stewart and Rachel Hunter. (Photo by Ron Galella/Ron Galella Collection via Getty Images)

Stewart has eight children with five women. The only one not pictured is a girlfriend with whom he had a child who was given up for adoption in the early 60s. They remain estranged, while the daughter has reportedly patched things up with her father.

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Stewart, 74, is most famous for a string of 70s and 80s pop rock hits, including "Hot Legs," Do Ya Think I'm Sexy?" and "Some Guys Have All the Luck." He first hit the rock scene as the lead singer of the 60s outfit the Faces, alongside Rolling Stones guitarist Ron Wood.

Alana Hamilton and Rod Stewart attend their wedding reception on April 6, 1979 at the L'Ermitage Restaurant in Beverly Hills, California. (Photo by Ron Galella, Ltd./Ron Galella Collection via Getty Images)

Alana Hamilton and Rod Stewart attend their wedding reception on April 6, 1979 at the L'Ermitage Restaurant in Beverly Hills, California. (Photo by Ron Galella, Ltd./Ron Galella Collection via Getty Images)

Stewart, who was knighted in 2016 (making Penny Lancaster-Stewart his only wife who is also an official Lady), once said of his penchant for marriage and divorce: "Instead of getting married again, I'm going to find a woman I don't like and just give her a house."

Penny Lancaster, Rod Stewart & daughter Renee Stewart (Photo by L. Cohen/WireImage)

Penny Lancaster, Rod Stewart & daughter Renee Stewart (Photo by L. Cohen/WireImage)