I have an 11 month female, spayed pit named Luna. She is extremely sweet, friendly and loving. I also have a 3 year old nephew who Luna protects as if he's her baby. When someone comes over, I can't get Luna to stop barking. She will run towards the person and bark, her hair sticks up, but her tail still wags. It is only when we are in our home/on our property. There have been a couple incidents where my nephew has been in the room with me and Luna and my nephew's Dad came in the room to tell me something using an angry voice and the dog would growl, then she lunged at him and tried snapping at him when he kept using the same tone of voice. She has done the same to my nephew's mother when my nephew was sitting on the bed with me and Luna, and his mother came into the room and suddenly started tickling my nephew. Luna lunged and tried snapping at his mother. If someone comes to the house when he is around, I cannot get the dog to stop growling or barking. The dog and my nephew absolutely love each other. She is so patient and loving with him. But is there something I can do to help her to realize a person is okay and she does not need to be so protective?