Okay the reason I am so urgent about this is that I want to start working with the dog immediately, because if he doesn't show signs of improvement soon, my mother will be getting rid of him.

I have three dogs: Holly, Spike, and Jackie. Jackie is a pure bred Jack Russel Terrier, also the mother of Holly and Spike, though we do not know who their father is. Many people, including vets, have pointed out how well behaved Jackie is for her breed. She is sweet and gentle, and good with kids, strangers, other dogs, and cats. Holly, though she is hyper and overwhelming often, is pretty much the same way,though she likes to try and "play" with the cats, and ends up chasing them around. Neither of them are that big of a problem, in fact I am training Holly currently, for she is my dog. Spike however, is my sister's dog, and he is a very sweet dog, but only to the family. When it comes to strangers he snarls and barks and growls at them. He sometimes even snaps at them. Just today, and teenage boy was walking, and he bit the boy in the leg. (Hence why my mom wants to get rid of him) This was the first time he actually but someone. He drew blood and got him pretty good, but not so bad as he needed to see a doctor or anything. He is also very good with our dogs, and two of the other neighborhood dogs, but all the others he tries to fight with. Two rather aggressive dogs down the road, he likes to taunt when they are locked away on a porch, by jumping at them and barking aggressively. We try to keep him leashed, but he sometimes slips through the door, and then we have to go find him immediately. The thing is, he will not listen to "come" when he isn't in the house or on a leash. When you kneel to get him, he will tease you, by coming near them jumping back, or running circles around you. We usually have to lure him in with treats, which can take up to a half hour-45 minutes.

I really need tips on training a dog like this, because I don't know what else to do for him, and he is my sister's best friend as well as a loved member of the family. PLEASE PLEASE PLEASE help me!

P.S. Jackie, the mother, is about 5 years old. Holly and Spike are maybe 22 months or so.