I've only worked hazel a few times and didn't have the same problem straightening it with dry heat. Mine came from Utah suburbs and coastal Oregon. One 3 or 4" dia. stave had some weird front/back wiggles, but I was able to match up the bends top and bottom limb, to make a slight setback handle and dead flat limbs just with clamps on a board and dry heat. That was a bit of a trick because most of the bends had to be right in and just off the fade-out areas, so a critical spot and fairly thick. But it stayed fine.
The only advice I think I can give you then is to get the bows as close to final dimensions as possible, over correct on whatever forms you use, use oil with the heat, and cook it good and golden.
Good luck, way to take care of the kids.