They're very cute! However, if you don't mind me mentioning it- I believe your minis need a bit of a diet. They are both atleast 20 pounds overweight. I know that a bit of it is winter fuzz, but they definately have very excessive fat. As a fellow mini owner, I know its really hard to keep the weight off of them, especially in the winter- but extra weight is hard on miniatures joints and it can cause cushings, laminitis, and founder- all deadly diseases.
Now on to comformation. I like Hope. Her back is nice and short, and she has fair bone. I dont like how her neck ties into her withers and her withers seem a bit muttony, but this may just be because of her weight. Her legs to toe out but not terribly. Her back isn't as straight and well formed as I'd like, but that shortness is a good quality. Without the big belly, I also think that she might have a bit of a shallow heart girth, which may affect stamina. Developing a topline will help her a lot. All in all, sure. I think she could pull a cart. Whether she'll enjoy it or not is the question! Just get her in shape before you try anything strenuous. Her height is great for carting.
Duey- this guy has a few more faults. He has almost no defined chest and I dont like how his neck ties in to either the chest or the withers. How old is he? He's butt high. If he's Hopes age or younger that might go away, but otherwise it is counted as a fault as it makes him carry himself more on the forehand. Good front legs, and a very cute face!