How am I going to convince my parents to get a dog?

Your parents don't want a dog. You have no business checking out their bank status. She told you that you can have a dog when Christina gets a dog, but she has a cat. That IS the point! Christina does NOT have a dog, so you aren't getting one. If you type YOUR question in the search box above, you will see this question has been asked thousands of times. Both your parents AND Christina's parents don't want a dog. Case and subject closed.