I just read your post in the Doodle Whisperer group. This photo proves how much Cody is clearly a part of the family - I hope you can get a helpful trainer or whatever else is needed! Hugs!
I hope you will have Cody's thyroid tested, fire the trainer, and get one that understand's Cody. I think you need a short term plan regarding the children to keep them safe, and a longer term plan for Cody's training. It is certainly worth trying something different before giving up the dog, as long as the children give him space for a while. Good luck and keep us posted on Cody's progress.