Hi mate,
The fentanyl pateches will certainly help the oxy withdrawals dramatically, how well though depends precisely on what strength patch you are using.
To make the process as WD free as possible, taking 3 tabs instead of 4 for 3 days, then decreasing to 2 tablets for 3 days, then 1 tab if once a day if/when needed for a week, then stopping should make it almost withdrawal free with even the entry strength fent patch.
If you need to take half a tablet, as they are capsule form, a good way is to dissolve the tablet in a medicine cup with 50 mls of water, then drink half and refrigerate the rest of the liquid (it will stay good in the fridge for at least 3 days)