Agressive New dog

Question
48 hours ago we adopted a 2 and a half year old female boxer from
the county pound. She was found as a stray. We introduced her to
our other two boxers one is a 5 year old female the other is a 6
year old male. We also have a 1 year old Jack Russell terrier. In
the 48 hours we have had her she has gotten into two fights with
the male boxer (drawing blood she took a small chunk of his ear)One fight with the 35lb Jack Russell she did not draw blood. She
has snapped at the other three dogs anytime they got close to us
while we are petting her. When she is not fighting with them they
play with their toys together she also licks the male and female boxers ears. Do we hire a behaviorist or just take her back to the pound rather than take the chance of more aggression. Really need
to know because we are seriously considering taken her back to the  pound.I'm not used to seeing this much aggression in a boxer.
It really has me thinking I made a mistake by adopting another dog.

Answer
I really hate to say this.  We are slaughtering millions of dogs every year for lack of homes.  She may as well be one of them.  If you still think another dog would add to your life, take her back and save a dog that won't be as much work.  

Nobody knows everything.  I don't have the training and experience to help you with such a dog.  i can't even promise a good behaviorist could if you foiund one.