Sir Elton John and David Furnish are hoping to father a second child this year.
David, 49, has revealed he and the Rocket Man hitmaker would like to give one-year-old son Zachary a little brother or sister, and are thinking about enlisting the help of a surrogate once more.
He said: "I would like Zachary to have a sibling. I think he would be better with a sibling than on his own. It's something we talk about all the time. But in terms of when, where and how, nothing's decided yet.
"I think we are going to wait till this summer (winter, NZ time). Our life is always like a treadmill with Elton constantly working and touring. But when we go away to our house in France, that's when we sit back and go [big exhalation] okay, how is this working, how are you feeling?"
The couple - who met in 1993 and became civil partners in 2005 - both donated sperm the first time around so they don't know which one is the father, and plan to do the same again.
Explaining the process, he told the London Evening Standard newspaper: "We could go back to the same egg donor, so biologically there would certainly be a connection between brother and brother or brother and sister."
However, they may need to use a new surrogate mother because their previous one, "has been a surrogate before but has a life of her own and her own family.
"It's a big commitment to make, nine months of their life that doesn't just affect them but their children, their husband, their partner. If we found a surrogate who is half as beautiful as our first, we would be very lucky."
- Bang! Showbiz