8 Month GSD, Poor Focus/Protection

Question
I have a (soon to be) 8 Month old Pure bred German Shepherd. Male, not neutred, 92 lbs and very smart. My Wife and I have been training him and he has already graduated obedience school with no problems. He is very smart and disciplined. However, when I take his "Sister" (my wifes mutt dog) around him, he COMPLETELY ignores me and will not pay any attention to me AT ALL. If I scream his name he won't even look at me and she will. He just focuses on her and waits for her move as he is sooo excited to play with her. It is very frustrating as when she is out of the picture he is a very disciplined dog. She has been with him and kinda took him as her "puppy" when we brought him home @ 6 weeks. We live on 409 acres and they have all the time and space to run around, so thats not an issue. Also, I am a little worried about his "protection" skills. If strangers show up, she barks and goes crazy. He wags his tail and greets them with a lick.  However I was outside walking from feeding my horses (it was dark and i live in the country) and I approched his kennel outside and he growled. He didn't know who I was I suppose, and I think he was attempting to defend himself. I didn't say anything as I was impressed to hear his growl for the first time, but when I approched him and also made a "growl" noise to really live up the situation he retreated but barked. Then I called his name and he was calm and that helicopter tail went crazy again. When he was maybe 4-5 months old and I exposed him to some cattle working dogs (ones we use for running our cattle) my GSD did not stand down an inch and was almost trying to establish his "Alpha" amongst the bigger, older, and more intimidating dogs. I was acctually impressed. So basically, should I not be concerned until he is 1-1/2 years old? Both of his parents were very, very protective. Should I be worried about that also? Thanks.

Answer
Actually things maybe going quit well as far as protection goes.  A good protection dog takes its clue from its leader.  It you are confident and pleased to see somebody, then he needs to wag his tale and greet them with a lick.  When you aren't around to signal approval, then he needs to challenge whoever is prowling around in the dark.  

I am much more concerned about him ignoring you around the other dog.  Perhaps he may know his commands, but do you know your role?  The key to most behavior problems is approaching things using the dog's natural instincts.  Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog.  Life is much easier if the 2 legged pack members outrank the 4 legged ones.  You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/  For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

You might start out working him with her near by, but not assessable, perhaps on the other side of a fence.  Start back far enough he will focus on you.  Drill him on his commands for a while.  Some other day, start a little closer.  Try to work him closer and closer without losing focus.  Neutering him could add to his utility for protection.  Distracting a dog with a female in season is an old trick.