Their children were being looked after at Wartegg Castle in Switzerland by Charles 's step - grandmother Maria Theresa .
Zita managed to see children in Zurich when her son Robert needed an operation for appendicitis .
Their children were being looked after at Wartegg Castle in Switzerland by Charles 's step - grandmother Maria Theresa , although Zita managed to see them in Zurich when her son Robert needed an operation for appendicitis .