Details! Finally! ;)
Daisy was excellent at picking up the ground driving. Lydia came to the barn to be my assistant, and at first, every command I gave I had Lydia reinforce at her head. Within a short time, I had Lydia walking farther and farther away from Daisy (which scared Daisy, I think. She kept trying to follow Lydia anyway ;)) ) until it was just me and her. She did wonderfully! We were walking and turning circles and figure eights and stopping and backing.
Sydney gave us the advice to practice dragging things, so that's what I've been doing. Sunday I started small with just a jollyball, but she obviously did that fine ;) so yesterday we dragged a wood ground pole. Granted, it is a sandy arena floor, but the pole did scrape against stones randomly, and it didn't bother Daisy at all, at the walk or the trot. Maybe it's ridiculous, but I actually have hope that she could learn to drive. Today (or tomorrow if we run out of time) I'm going to drag a barrel with her. (by drag I mean sitting on her and dragging it by holding on to the longe-line it's tied to.) If she takes the barrel in stride, I may just ask for a harness for Christmas. Who'd a thought Daisy could be a driving pony? :)
Thanks Sydney for all your help!