I've never asked for anything from a CM or Guest Services, but I've read a LOT of trip reports and if I recall correctly, you may be able to bring your own little surprise treats for them and have Guest Services put them in your room each day when they do housekeeping. That is, of course, if you're staying on property as a regular guest and not a DVC member (DVC guests don't get housekeeping every day as a way to keep the membership dues down). ANYWAY...you could have little packages that they bring that are from Mickey or Minnie or Tinkerbell or Pooh (you get my point...whoever their favorite characters are).
OR...instead of relying on housekeeping or guest services...just do it yourself. Keep their goodies in a suitcase that stays close to you in the room then, when they aren't looking, you can put their surprise on their bed. Maybe get them some T-shirts w/ their favorite character for one day, and then maybe a character signature book, or just a bag of their favorite candy to take to the parks, or a disposable camera for them to take their own pictures to send to your dad.
Also, while you're in the parks, if you're staying on property, you can purchase an item and have it shipped to your room...that might be an idea for the kids if they see something they really like you could purchase it while they aren't looking and have it shipped to the room.
There's a thread on here somewhere that you can have another guest send you a postcard from Disney...maybe you could locate that thread and have someone who's going down there soon send the kids a postcard from their favorite character telling them they're looking forward to seeing them. (I think it's called a "Pay it forward thread") But I can't remember if it was on the "World" side or the Cruiseline side of these threads.
Well, those are some of my ideas. I hope you all have a very magical vacation and God Bless your dad while he's in Iraq!