Hmm, perhaps you can make a list proving you will be able to take care of all it's needs (vaccines, food etc)
A list of everything that it needs
have the time/plan to train it
the perks of having a dog
Make a lil contract if you must so they know they can trust you will take care of it's every need
it helped me somewhat when it came to convincing my mother ( since i still live at home , rip)
So my dad is angry because my laptop is not doing what it should be doing. When I got no problems with it. He says I keep on trying to type an email but then other stuff pops up. At that moment I see a website show up. Well let me tell you if that website pops up you clicked somewhere in the browser you should not have clicked,