A crazy idea?
I bought a valved harmonica time ago, and I thought it wasn't a good election for me, but I became aware about the musicality it had in the lower blow holes.
People use to complaint about 1 and 2 draws, but I find that I don't get the tone I want in the first, second and third holes blows.
Could valves solve this problem? I am thinking about valving the three first blow reeds.
Valving the inside of the draw slots will close off the draw reeds when you play a blow note, and make all the exhaled air go to the blow reeds, making them louder, and will also make the blow reeds bend more easily.
I think this is what you intend to do. That's what is done usually on half-valved diatonics.
If you put valves on the outside of the blow note slots, then the blow notes won't be any louder and the draw notes will instead get louder but they will no longer bend normally because the blow reeds won't get any air during an inhaled breath and can't participate in the draw bends.
It's hard to tell what the solution is without a good understanding of the problem.
What are you experiencing in the first three blow holes on your valved harmonica?