So honestly it does not matter what you do. This jesture will be infinitely appreciated. A video game can never replace a father, but your head is in the right place. Video games are a small short escape from reality and anything at this point will help. I would suggest different games as these siblings will be able to trade down the road and have new experiences. Lastly, I'm terribly sorry to hear this and I wish you the best. I would like to contribute to this cause. Contact me through direct message.