When charging at an enemy unit, must take the most direct route to the enemy.
Does this places the attacker in the center of the defender?
Can he charge any part of enemy base?
Sometimes another attacker would fit only if the other attacker shifts a little.
In some games it was done this way. Charge was possible only if the new model fits or if the current engaged friend is able to shift a little.
Also, it is clarified that corner-to-corner is not enough for melee. It probably means that corner-to-side is also not enough and probably should be changed to that.
Any way, it is problematic when units are engaged over an obstacle.