7 month old pure bred Ridgeback male (intact). Had him since he was 6 weeks old. Parents have tried training him from day one to no avail... He is extremely boisterous, highly excitable and completely uncontrollable - to the point where people dread going to visit my Parents. He jumps up, paws and bites people (both strange and familiar) and because he is a big dog already, he does quite a bit of harm - he has already bitten me in the face although it wasn't intentionally aggressive. My folks have to resort to physically restraining him because he won't listen to instructions/shouting/threats, and they end up getting hurt in the process (Mum recently sprained her wrist trying to hold him by the collar). They can't even lock him outside for a break because he throws himself at the glass door. He also pines after my Mother if she goes out and goes absolutely crazy when she gets back. His problem is that he's over-exubetant, will not listen to anyone and quite literally runs riot. A little exuberance in a puppy is fine, but a lot is not, and may turn into uncontrollable aggression as he gets older. If we have no way of controlling him now, we certainly won't have any control over him later.
However, he does listen to 2 instructions. He will sit for his food, and he'll go to his basket at night when being told, but only because he knows he gets a biscuit. My Parents look after my 8 year old daughter after School, and oddly enough he has on occasion listened to instructions that she gives him, which is more than he does for my Parents.

The first course of action is to have him neutered.
He is going to be a large dog and this is totally unacceptable behavior.
Intentional or not, injury to a visitor or your daughter could be a disaster.
Obedience training is a must in their situation, training is not only for the dog but also for the owners, so they will have to be very involved in the process, both of them.