Our dog is 15 months and will still mouth at times but fortunately he doesn't close his jaws. He will also jump up at DH and the kids sometimes, but not me - I'm definitely the alpha in our house but that is purely because I'm the most consistent with him.

We so a combination of "no", the knee up and telling him to sit and stay, with rewards of either cuddles and pats or food when he does. Most of the time it works pretty well but if the kids are running around screaming then its pretty hopeless and we just separate him from them. He is always last through doors, on the floor and lower than us.

Our biggest problem is that while he is gorgeous, he's a bit of a ditz. Hopefully your shepherd is a lot cleverer!