It is definitely possible to replace factory presets with the Soundtower P12 Editor.
I have (had)
one with corruptet factory presetsm about 25 an all four banks.
Strange names and sometimes erratic sounds too.
The Soundtower editor did the job perfectly (one can overwrite every single patch).
In fact it even doubles your memory space from 400 to 800 presets.
Great work and its worth every single buck.