[JoeyP]

To get a dog over the fear of someone or types of people try this

Have you grandfather come in
Have him not greet or look at the dog no matter what the dog is doing
and have your grandfather just drop trats on the floor at regular intervals
Your pup will come and take them
and as he does this have you grandfather drop them closer and closer
until the pup is taking them from his hand
Then he can look at the dog while giving him treats
Your dog will eventually get the idea Hey this guy isn't so bad after all

When he goes to greet the dog even if he has a treat for him
he is perceiving that as a threat