Welcome to YorkieTalk, Liz and Diddy! Diddy is a genius doing all those things! Higgins is so busy playing with rocks, I can't get his attention long enough to teach him much! He's not the scholarly type, despite his name.
Funny though, he still likes to "play bite" Don's hands....because Don LETS him! He NEVER play bites my fingers because I wouldn't let him right from the start. However, he gets more treats from his "dad" who can't resist him looking cute. I play with him more because he has learned to sit up and beg for me to throw his toy and he knows I can't resist that. So I KNOW that little guy is smart! He knows just how to manipulate us to do what HE wants!
......and we love it......we're sunk......sigh.........