there IS a way to use three keys to accomplish this task...
if you assign each character to a key, let's say 'B' for Dk and 'N' for hero, you can also assign (let's say) medium health potions to the 'M' key.
this way you're switching between the characters and which-ever you have selected will be the one drinking the heal potion(s).
you could also assign the mousewheel (up and down) to this task...but i prefer it for zooming in and out. for that matter, even mousebutton 2 and 3 would work.
not sure if it's all worth it though...your decision.
sadly, assigning 'lead character' to (let's say) 'V' will only switch who is the leader, NOT who drinks the potions - so they must be assigned independently.
