May Allah make it easy on your aunt. She has to pray on time and in clean body and clothes. These are two of the conditions of prayer.
If she can remove the pampers and pray clean after washing, if she can make wudhu and if she can pray each prayer on time, she should do that. But if she is unable to pray clean due to her continuous urine problem, she can pray as she is.
If she can’t perform wudhu because it is really too painful or due to her injuries, she should wash the areas she can and then perform wudhu on behalf of the rest.
If she can’t pray on time due to fainting or because it is too hard for her to clean herself and perform wudhu 5 times a day, she can combine Thuhur with Asr and Maghrib with Isha.