have you tried time outs? praise when he licks instead of biting? the second pup bites, he gets a timeout. A timeout consists of 10-15 seconds completely cut off from you aka behind a closed door. Bathrooms work well for timeouts but make sure there's nothing pup can get into. You can also work on licking instead of biting but using a stick of butter. Rub a little on the back of your hand, allow the puppy to lick the butter spot, praise for "kisses" and treat. Repeat. Enourage pleasant behaviors. Dont reward the bad.
The more people I meet and talk to,the more I love my dogs and their intelligence.
Shasta GSD 5/5/10 CGC
"Dax" Thor z vom Weberhaus 3/18/2013
Zena GSD 6/1/03
Riley GSD/BC 1/10/05-2/1/2013