What can I do about this?

There is a dog at the shelter I work at that I would like to adopt. The only problem is that (a) my dad says no, (b) we don't know how our two dogs would react and (c) the dog I want to adopt might be dog aggressive. He seems to get most aggressive whenever we bring another dog out and I'm around. Or if we're in the room where he almost always is. I want to know how I can convince my dad to let me adopt him, because the dog has taken to the idea that I'm his owner, and no matter who pets him and gives him food it's always me he comes back to. Plus, if I adopt him then I'll have made sure he got a loving home and that another dog can be rescued. And, does anyone know how I can try to train him not to be dog aggressive? Thanks! And please, give me helpful answers, nothing like 'don't adopt him' or whatever. And please, I'm not going to do anything to hurt him. No shock collars or deprivation training. So, if you could help I would be immensely grateful!