If you had a diatonic harmonica for every key, can you stack them in such a way that they cover the piano key board? One more question..what's the difference between playing in 2nd position (cross harp) and playing a song in the key of the music on the lower end of the harmonica? I guess I should of titled this post "questions".

First question: Yes. ... Well, you could cover one octave of the keyboard, or even more, if you have high or low key harps (such as low F or high G.

Second question:
Suppose you want to play a song that's in the key of C. If you play it on a C harp, You're playing in first position. Most of the notes will be available to you by simply blowing or drawing without having to use bends.

If you want to play that C song in second position, you'll need to play it on a G harp. You'll be playing the same notes, but through different holes. For some of the notes, you'll need to do some bending. That's what allows for that blues-like expressiveness.

Ok, I'm looking at a tab called "Lonesome Whistle". It has a hi and a low. The high is in C first position. Is the low just C an octave down or is it cross harp in F? By the way, nice tab and thanks for moderating.

Thank you. I don't moderate, though. I just help out a little in some very minor ways.

Those are both in C; just different octaves.

I can play in second position, but I'm trying to learn how to look at a piece of music and say, "this would work in 2nd or 3rd position" and here's how I would do it. And, sorry about thanking you for moderating. The word "moderator" by your name threw me off. Seriously, thanks...you are always very helpful.