A tactic that I thought I'd offer:
What functionally is the difference between wetting one's diaper without forethought (an accident), and wetting with no memory of forethought? A few seconds after wetting starts, the difference is only the memory of that forethought.
Urination involves the coordinated action of consciously controlled and unconsciously controlled muscles. Altering their behavior in a way that still mostly works isn't easy. In contrast, forgetting involves simply not remembering.
Perhaps a suggestion to forget the use of control could be used as a stepping stone towards a conditional lack of control?
Without this tactic, wetting in diapers would ideally take progressively less forethought, until it becomes automatic. Until that happens, the memory of the forethought will be a reminder that it hasn't happened yet. This might bring into question whether it ever will happen.
If the suggestions were structured so that wetting when wearing a diaper would become automatic and that any forethought about wetting in a diaper would be forgotten, this would eliminate that memory and that question.
The subject would either realize that he or she was wetting, or that his or her diaper was now wet, with no recollection of deciding to wet.
Of course, the subject might still note that he or she doesn't remember starting to wet, and remember the suggestion to forget not having had an accident, and know that he or she didn't have an accident this time. To prevent this, there would also need to be a suggestion to forget the suggestions.
Any thoughts?
Feel free to use this tactic.