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.