9 yr old boxer trying to attack new puppy.

Question
we recently lost out 17 yr old boston.  We have a 9 yr old Boxer who was a rescue.  They did get along but the boxer was the new guy.  We recently got a new 3 month old Boston and the boxer will try to attack her. We have to keep the puppy in a crate when ever they are together.  We have been giving the Boxer treats and love whenever they are together but nothing seems to help.

Answer
She is probably trying to dominate the puppy,a trick that usually works is this:let the boxer play with the puppy in the yard,but put a muzzle on the boxer,so she can't hurt the puppy,and she will soon realize the puppy isn't going to hurt her and eventually you can take the muzzle off,but put leashes on both dog for a while(dragging them)just in case anything happens