What would you like to change in Heroes of Might and Magic III?

add the ability to transfer a castle to an ally

Why? Who would give their city to an ally?;)
I, on the other hand, would add the ability to take artifacts from an ally during a trade, because in the last game, his heroes have 2, or even 3, Spheres of Vulnerability each, and I have none! :( And since it's AI, asking him to share is pointless!