We just got our puppy 5 days ago. He is about 8 weeks old. He has been aggressive towards our older boxer by biting on his back leg and not letting go, until we pull him off and tell him no. I know our older boxer starts him on the mouthing, but then the puppy will grab Radar(older boxer) by the cheek and won't let go. We don't want our puppy to play so rough, because he might be even more aggressive when he is older. Do you have any tips on what to do? Also, he likes to chew on anything and everything and Radar was never like this.