Daddies on duty!

Sir Elton John and Neil Patrick Harris got their families together for a playdate Thursday. John, 64, partner David Furnish, and their 7-month-old son, Zachary, were all smiles with Harris, 38, fiance David Burtka, and their 9-month-old twins Gideon and Harper at Club 55 in St. Tropez, France.

"[Elton and David] are great guys," Harris told Access Hollywood earlier this year. "They're super great parents. They're so fiercely involved in their son's life, and it's really kind of great to watch them interact with him."

The How I Met Your Mother star is a pretty involved dad himself. In a June appearance on the Late Show with David Letterman, the actor proudly showed off pictures of his twins in festive costumes. "We take one [picture] a month. We're doing a calendar, so that when we're older, we can humiliate then," he joked.