Is there a way to assign damage to multiple defenders?
Solution 1:
In the normal tabletop card-game, if there are multiple creatures blocking one creature, it's the attacking-player who gets to choose what order to assign the damage.
In Magic 2012: DotP, when you are the attacker, by default the computer chooses an order for you (to keep the game "simple"). You can however change it so that you get to decide the order every time by going to Settings --> Advanced --> uncheck "Auto assign damage."