I'm one that always tells it like it is, so here goes. I would never have let her take her first shot at a deer that was over 200 yards away, especially with the .243. The deer at 34 yards quartering away that ran into the swamp over 50 yards away with no evidence was probably also missed. Why did the deer you say you shot near hers with your 30-06 go that far and did you find it? I think you're making a big mistake going up to the 30-06 for her with all the problems you've mentioned with the .243. Shooting a bigger caliber, IMHO, is just asking for more problems. If she couldn't hit either of those animals, using that bigger caliber won't do any good because you still have to put the bullet in the vitals no matter what caliber you use. The .243 or even moving up to a 25-06 is more than enough gun for that girl IF she does her job and again, IMHO, doing all of what you just stated with a bigger caliber isn't going to help her one bit and may exacerbate the situation.
Good post and that is pretty much how it is. Get her to shoot that 243 a lot between now and next season. Get her away from the range and out in the field to shoot. You'll have a lot better chance of her getting her deer that way.