We aren't sending books to charities (unless asked). We're sending money.
Kickstarter does NOT allow funds to be directly given to charity. Therefore, money over the stretch goal will go into purchasing additional copies of the book. These copies will be sold at non-Kickstarter venues (conventions like AnimeExpo, galleries like Gallery Nucleus) and the money from those sales will be donated to charity.
Keeping track of post-campaign sales and then splitting it among 100 artists would be a nightmare, so they all agreed to receive a flat fee (covered by the campaign) and let the rest go to charity.
At the moment, we intend to support Wild Spirit Wolf Sanctuary or the UK Wolf Conservation Trust, both charities previously supported by George R. R. Martin.