I have the same problem with Cooper, he will not allow anyone near me, he even growls at my husband. He does not like kids at all, so, I just put him in his kennel when we have company, with a treat. He does not like it, but I would feel horrible if he bit one of our young nephews, like you would feel if she bit one of your grandchildren.
It took him a long time to make friends with our old housekeeper (when we used to have one

), but he did, and the first time she brought her son, Cooper jumped off the couch and bit his hand on the way down when he got too close to his Mom..it did not break the skin, but that is not the point!
Baxter and Darcy would probably jump in a strangers car and ride off, they love everyone...Cooper only likes his Mommy, and sometimes his Daddy