Same as with the tips. If the area is too thick still, reduce it to the finished size first for easier bending. Deflexing isn't going to pull out like some reflexing and recurving can. What wood are you using and where do you want the stave to deflex?
I use mostly osage and it bends easily compared to other woods so dry heat is my preference. With some other woods, boiling or steaming is the ticket. In thicker areas you have to be sure the heat goes all the way through the wood and not just hot to the touch so longer periods of heating will be necessary.
You could always overstress the stave. That will definitely deflex it!
Just kidding!!!