Visiting Jack Russell & Aggression

I have a 4yr old JR girl, my daughter has a 1 yr old JR girl. Last year my daughter and her puppy lived with us for 2 mos while her husband was at Army Ranger School. All went well, until the puppy started to get very territorial about toys, treats, and attention, my 4 yr old then started to act that way too. They would play well alot of the time, but then started to get very aggressive with each other, if there was something at stake. We had to pull them apart about 6 times. The last time ending with the puppy biting my husbands thumb as he tried to separate them.
My daughter and pupply returned to NY in early January. Now they are back for 18 to 24 mos and they are going to be living 1/2 of the time with me and 1/2 of the time with my daughter's father. The first month will be spent at his house. But in the 2 days that my daughter stayed here we had to pull them apart 2 times. Once when they were playing and they got too wound up, the 2nd time when they were anticipating a treat.
Do you think you could help us? The 4 yr old had obedience training as a puppy, will sit, give paw, stay (sometimes) and the 1 yr old can sit and stay, but has had no training. We don't know if a regular obedience class with other dogs would be the best, or if private classes would be needed.
PS. Since after my daughter left the 1st time the 4yr old has become aggressive towards other dogs that she was fine with before!

• Re: Visiting Jack Russell & Aggression May 12 (0)