“Discussed with Elon and, in light of beautiful Arcadia’s birthday, we felt it was better to also just share directly about our wonderful and incredible son Seldon Lycurgus. Built like a juggernaut, with a solid heart of gold. Love him so much," Zilis wrote, also revealing the name of the couple's previously-born child in the announcement.

He has five kids with ex, Justine Wilson, including twins, Griffin and Vivian, born in 2004, and triplets, Kai, Saxon and Damian, born two years later. Their first son, Nevada Alexander, was born in 2002 and died at 10 weeks old.

Finance ministers and central bankers from the G20 top economies gather in South Africa on Wednesday and Thursday, for a meeting marred by the absence or curtailed attendance of key members and disputes over the main issues of climate, debt and inequality.