cant we all get along!

Question
I have a new puppy!  Bella is a 12 week boxer/bulldog mix.  She is more boxer than bulldog.  We also have a very submissive 17 year old Bichon male.  The new puppy is VERY jealous.  She also (I believe) wants to establish her dominance in the pack.  She will nip and bite the older dog.  He, on the other hand, really just wants to eat, sleep, and get some attention.
Bella has been very easily trained on "sit."  Still, she is the typical stubborn boxer.  She will "leave it" or "sit" when it isn't too irristible.
Any tips are greatly appreciated!
Thank you very much for your time

Answer
Once past 3 years old, many dogs don't want anything to do with puppies, their sharp little teeth, and their biting games.  You need to teach the puppy to leave the older dog alone.  As soon as the puppy starts to focus on the older dog, give it a sharp ''Ah, ah, ah!'' and offer it a chew toy.