Puppy Troubles

Hey, a serious question, for a change.

So at home we have this border collie. The collie is an incredibly smart dog, very obedient, does all those tricks and such, and is and always has been a very affectionate thing. However, she is also a bit of a coward, and doesn't like other people outside of family members and friends that she has seen a lot of. And other dogs-- shyeah, don't go there. She doesn't snap at them or anything like that-- more, she just cowers behind my legs.

It's not like she's unused to other dogs. We used to have a German Shepherd, who was a mellow dog until, that is, the collie (who arrived afterwards) would growl at her if she came near. Now-- no amount of telling her off, making her leave the room, whatever, would stop her-- inevitably, they got into some scraps. A fight between a dog that nips and shreds legs and a big huge Alsatian is never a pretty sight.

The older dog died a while back. We have a new puppy now, a German Shepherd again, who is frankly adorable. But also very silly and with a liking for jumping up and biting, as puppies are wont to do. He's really too young to be taught much at seven weeks old, though I have taught him to sit, at least, and he is very eager to please. However, my brother tells me that things are not going well with the dogs. He keeps trying to get attention from the collie, even nuzzling her for comfort-- which is always responded to with a growl. They were in the garden the other night, and she bit him so hard he was yelping in pain.

Am going to go home soon and be all authortarian and stuff, but I'm not sure what to do. I'm very good at getting the dogs to obey me, just not good at stopping them from biting each other. Any ideas, anyone? Or shall I just get the cat to deal with them both?