[Daren]

There’s a few problems with this:

The reed cavities, below the reed plates are sized to fit the reeds. This would cause problems when shifting different pitched reeds around.

Lower reeds are bigger, higher reeds are smaller.

There’s extra problems when using reeds from one make and trying to fit them into a melodica of another maker, as they have their unique sizes and spacing within the reed plate.

There’s also the alignment of the screw holes to fit the reed plate, which will be different for each make/model.

But in principle it works, though I think you’d have to make a new melodica 🙂