A good schutzhund trainer, or any good, strong trainer familiar with real dogs, not some feel-good clicker trainer, ought to be the first you go to for remedial training. If you are to try to salvage this dog, ALL family members must be willing to go to the training as well, you need it as much as the dog does. You may still end up needing to euthanize him. Rescue adoption groups, unless you touch a special heart somewhere, generally can't take on aggression problems.
The guy I know well is here in Washington State, and is expensive probably, but he's a Dog God. He trains and competes worldwide with Schutzhund dogs and sells them to police departments. I'd FRMail you his contact info if you are willing to transport him to W WA.
When we were still going to Schuntzhund and having trouble with nipping we asked a club member of long standing to help us. He said he would take him into his home (little children present) and work with him, for a price. We had walked around the track with him and he said he had seen nothing that would concern him.
We didn't do that (I really didn't think he should be around children, yet-- because he was a puppy with no sense) but did take him to a lesson with another club member that does training of Dobermans. She gave us the hand down the throat method and making sure we were dominate because our dog wanted to be very dominate.