Hello, I think I can help you. It seems that your mother has been on quite a bit of narcotic pain medication and she likely has a very high tolerance. 150 mcg of Fentanyl is equal to 495 to 584 mg of oral morphine (in a 24 hour period). 150 mcg of Fentanyl is equal to greater than 200 mg of Oxycodone per day (I can t find a good conversion for anything more than 100 mcg of Fentanyl). Therefore, I think it would be prudent to start with just the Oxycontin and Oxycodone and monitor her carefully. If she has any signs of withdrawl (usually nausea, vomiting, stomach pain, or increased pain in general), you could start her on 100 mg of the morphine twice per day. I think the reason why the doctor prescribed it this way was because these medications do not come in such high doses and it is difficult to get the prescription for a very large amount since they are controlled substances. He or she had to combine many different medications in order to obtain the same amount of pain medication as the Fentanyl patch. If someone has never taken narcotics before it would be extremely dangerous to take these medications together. However, your mother seems to be very tolerant to the effects so she should be fine if you titrate them slowly. Hope this helps.