I did some local research, and there is a trainer just about 5 miles north of us that teaches driving lessons. We may go ahead and get a mini, learn driving with it, teach little girl how to care for a horse with the mini, and she will learn to ride on the "big" horses (I say big but to tell the truth, they are kind of small QHs
). We would keep the mini "with" the horses, but not in the same pens. Mini would have his/her very own paddock and be turned out alongside but separated from the bigs. If they all get along swimmingly, we'll go from there, but for now, we may just look into keeping them separated but close to each other.