Our 2-yr-old GSD has bitten 4 people and is dog aggressive. Our breeder is willing to replace the dog but we wonder if we can do something before sending it back.

I have a two-year-old German Shepherd that is of 100% German descent. I bought him when he was 11 months old and he was obedience trained and had all the basics down. I planned on taking him to advance obedience training but he was very dog aggressive and attacked my friends dog in the park when we were trying to acclimate them and attacked another dog at the groomers while we were waiting for our turn. Both of the attacks resulted in only minor injuries but in both I was not able to get him off so I was fearful to take him into a situation with many dogs so we didn't attend class. He has also bitten people three times, two were accidental and one (the most recent) was unprovoked and on purpose. He bit my husband when they were playing ball and both were going for the ball at the same time but Evan (my dog) missed. He also bit my sister when she was holding her dog (he had gotten out of the room he was penned in) and he went for the dog and missed. Both of those bites resulted in broken skin. The latest bite occurred when my oldest daughter though she would be funny and let him out of his kennel in the garage when my other daughters friend was over. Neither the dog nor the child knew the other was there. Evan bit her thigh and then backed up and held her until my husband came out of the house and threw him in the back yard. Evan didn't break the skin but she was in a definite hold and had she moved I'm quite sure he would have gone at her again. His obedience works has been hit and miss lately and he spends a lot of time out in his run that is attached to the garage. Could this be the cause? I have three children ages 10, 12, and 2. Do I need to be concerned that he will continue to escalate despite training and bite them as well? I read your articles on dominance and the only areas that I have been wrong in were allowing him to be in the kitchen while we ate and allowing him to sleep in the bedroom not on the bed but he was in the room. I should mention that two of his brothers are K 9 dogs. I've contacted the breeder to give him the opportunity to take Evan back versus me putting him down (which was my first reaction) and he has offered to give me a puppy (from a different breeding) and place Evan. Now I'm wondering if I should work with Evan first and try to solve this before giving him up. I have changed my mind back and forth on this 4 times so far so any input would be greatly appreciated.

Thank You!
Angela