The FAQ says that fatigue may be spend to add power dice, and then the overlord may play a Dodge card after all dice have been rolled. I think the best way to read this is that the opportunity to play a Dodge card occurs after the last opportunity to spend fatigue to add dice: that is, if you declare you're done adding dice and ask the overlord if he wants to Dodge, and he says "no", you still can't add any more dice, even though he didn't play the Dodge card. The reason you can't add more dice is because of the sequence, not because the card was played.
But we also know that the opportunity to play a Dodge card must occur before you reroll your dice due to an aim order, because an aim and a dodge cancel out; once you've made the aim re-roll, it is no longer possible for the attack to be dodged, and therefore it is no longer possible to play a Dodge card.
So we know that your last chance to spend fatigue comes before the overlord's chance to play a Dodge, and the overlord's chance to play a Dodge comes before you reroll the dice due to an aim. Therefore, you can't spend fatigue to add dice after using an aim to re-roll. Any other conclusion leads to a contradiction.