I have had Poppy for one month. She was abandoned so I don't know her history. Two vets thought she is a Jack Chi. She is currently 4 months old. She is great with my husband and me, but strangers are another story. She barks continually, won't let them touch her, even when they have been there for an hour. My grandchildren are all grade school age and are used to dogs, but she is terrible with them, too. She usually sits on my lap the entire time someone is visiting. What can we do to help her?