When is it permissible to appoint a proxy for Hajj for a living person?

Question:
May Allah reward you, Your Eminence, father. The questioner says: A woman came from Africa to Riyadh a few months ago. She is ill, and when she rides in a car, her illness worsens and her heart pains her for several days. The question is: Is it obligatory for her to perform Hajj by traveling to Jeddah by plane and then by car, despite the severity of her illness? And if it is not obligatory for her, is it permissible for one of her children to be appointed as a proxy to perform Hajj on her behalf?

Answer:
There is a distinction in this. If it is expected that her condition will end and she will be able to perform Hajj in the future, she should postpone Hajj until her condition ends, and she will perform it herself. However, if the illness is not expected to end, and it is a chronic illness that the doctors have determined is chronic, has no cure, and its end is not expected, then she appoints someone to perform Hajj on her behalf.