My dog HATES my new puppy! I dont want to get rid of her because of this!?

Now i know i will never let my parents do this but my dog who was a only dog for 5 years HATES my new puppy and my parents say that if she doesnt get used to her we will have to give her away because patsy was the first one here and is the family dog. I will not let them do that, we bought bella and she is now our responisbility! I think it is because Patsy wasnt around many dogs for 5 years and was used to all of our attention. We take her to dog parks frequently and she doesnt seem to have interest in other dogs, just frisbees or tenis . So we didnt think it woulld be a big deal. We introduced them out of her terrritory at a park and it seemed fine but now everytime Bellas in the room Patsy runs out or growls. Bella is so sweet and playful to her and just wants a friend but everytime she tries to play patsy snaps! Help! How do i get them used to each other!