If he has not been neutered, this should be step one.
After that is taken care of, I suggest that you start a training class with him. Take him all the way through canine good citizen and then on to agility if he does well. This will build his confidance and your relationship with him will grow.
Once you have him under control, you can allow supervised play with the other dogs. Never feed them or give them treats all at one time.
If this fails, you will need to have a behaviorist come out and work with you and the dogs.
You might also want to consider rehoming him so that he can be an only child.
Let me know if you still have questions.
