Dog Training Job - Malvern, KZN, 4093

My dog is about 4 years old he is a rescue dog when I got him at 4 months he was always nervous. Now he has become quite territorial and very aggressive towards some visitors and to my recently adopted son. We also recently got 2 rotweiller puppies and we have 2 other puppies that are about 3 months older than the 10 week pups. The aggressive dog is a mix breed and has always been a nervous dog he gets overboard love and attention but yet still is aggressive towards some family members and friends and he sometimes snaps at the puppies but not very often. I really need help . It's getting quite bad as he attacked my adopted son today.