ha I bet they are really cute to watch. My Maddie really is fiesty and picks on the bigger dogs too. It took sweet Copper a couple months before he really knew how to play with her (she is so tiny and so rough, like yours) She would take his favorite things and growl and chase him (with her tail wagging like crazy because it was just so much fun

) She did however have a couple puppy time outs for biting too hard.
Now he just lays there and lets her pull his ears and hair until he has had enough, some times he will hold her down with one paw and just sit there while she goes nuts, or they will chase eachother though the house. Then he will go somewhere that she cannot get to, and watch her antics from saftey
At first I was really worried that she would be to much for him to enjoy, but they have their own little way of doing things, and are best friends.
Oh and if you can, I would try to get them on tape because they are only puppies once and it is so funny to watch back later on