I was watching the 8th season of family matters today when at the end of an episode Steve got a chain letter and said he was sending it to his buddy Corey Mathews. As in the kid from boy meets world.
All the shows are linked. Some people would disagree but they're thinking too hard on it. In fact my theory is every Disney show is linked even if we haven't gotten cross overs. All it takes is for a group of fans to be vocal about something. Who's to say Lizzie McGuire won't some day get a second show and take her kids to see Hannah Montana.
Hell I'm 90% positive Lizzie met the family from even Stevens. I didn't even watch those shows and part of me remembers it being a big deal. But I could be wrong. All I know is hanging with Mr Cooper had mr Cooper be Michelle tanners teacher so they're linked. In fact most of the old shows are.
Although they also connect to newer shows as girl meets world has a cross over with Jessie. So that's why I'm sure all the shows are linked. Some day will get dog with a blog hanging out with Steve urkel as he gets on Zack and Cody's ship because he got a letter from Lizzie McGuire to come to Waverly place or some shit like that.