Dr Mohamed Omar takes over from Ambassador Mohamed Mohamoud.
Once the backbone of the country's agricultural sector, many of them are now elderly, visibly frail, battling illness and financially desperate.
The news was only announced to mourners in South Africa after a funeral mass had already finished.
Since Sudan's civil war began in April 2023, the scale of suffering is so vast that the UN has labelled it the world's worst humanitarian crisis.
Among them is a pledge for greater cooperation on nuclear energy, according to details released by the Kremlin.
The reunion of families and friends took place in the Ethiopian town of Zalambessa in the presence of village elders and religious leaders.
More than 70 people have been treated in three hospitals, the health ministry says, adding that most have since been released.
Devon Africa's four-year-old son Davin was shot dead in February, caught in the crossfire of a shoot-out between criminals.
Their families say they were arrested because assets belonging to Equatorial Guinea's vice-president were seized.
