ok we know you need a live sacrifice so what happens to their souls maybe that is how to kill them some way i dont know just a thought and not even a complete thought lol
I think that when a ninja dies his/her soul goes to the other world if not sealed and with edo tensei its summoned back the sacrifice's soul is at the other world so i dont think its sealed cause its not summoned back its just the body. i dont know if it makes sense...
When normal people die : pure world, and hosts are killed normally : we witnessed how madara killed fu through breaking his neck. ( the living world is called impure world. )
Other than that there's just the dead demon stomach :d
The host is a temporary vessel for the soul of the summoned...yet since its a sacrifice the soul goes to the pure world...wen the summoned edo tensei gets canceled(and not sealed)bough souls go to the pure world