Her mother-in-law, June Patrick, of Orange Farm, Gauteng, said she received the news from her grandchildren, who were still stuck in the Al-hol camp in Baghouz, in the east.
Patrick said the children had sent her a voice note.
“It was terrible to hear about Saadah’s death. But now my biggest concern is for the well-being of her children. The twins (a boy and a girl) are 13 and their younger brother is 6.
“We’ve learnt that it’s starting to get violent in the camp because of the overcrowding and lack of food and medication for the sick,” said Patrick.
Like other IS sympathisers, Modise and her husband, Patrick Modise, 41, were drawn to Syria in 2014.
Patrick Modise and their 14-year-old son have been reported missing, while the couple’s eldest son, Mohammed Mokoena, has been reported dead.
Mokoena was married to a 20-year-old Swedish woman named Tawba who, according to Patrick, was about to leave Al-hol and head back to her homeland.
“Although Tawba is a child herself, the children had someone watching over them. Saadah is buried at the camp, but the children don’t know where.
“I heard that my one grandson was recently beaten by a 60-year-old woman at the camp.”
Patrick said people at the camp had to beg for food because there was none available, and the worry prevented her from getting any sleep at night.
She said someone at the camp had lent the children a phone to send her the voice note.
“Ouma (grandma), can we please come home. We miss you. We love you. Do you know that ummie (mom) is dead,” said one child.
The youngest child said: “Ouma, do you have a sweet?”
“I’m begging President Ramaphosa and government departments to help. Any assistance would be appreciated. The children and wives have done nothing wrong - they just followed their husbands,” said Patrick.
The Department of International Relations and Co-operation did not respond by the time of publication.