If I recall right, Shinichi's dad and Kaito's dad were friends correct? I forget where I saw that on....I think it was dealing with the first run-in with Kid but I can't really remember.
I think the series really need to allow the relationship of Mitsuhiko and Ai to develop more. Maybe to a level of dating, plus for Ai that would be a great cover......who would suspect a former member of the B.O. to be dating a little boy?
Mitsuhiko and Ai are just so cute together........it doesn't matter what the age difference is....after all she still appears to be the same age as Mitsuhiko
To be honest I think Mitsu's only real resemblance to Conan is his intelligence [for his age]. If you think about it he is Ai's best choice if she decides to stay a kid.