Originally Posted by mom2pride
I would try the dally, but would never tie any rope attached to a horse's halter to the horn. Even if you made a loop and simply looped it over, when something happens, you're not going to have time to get that thing over the horn before it tightens.
Does Luna know how to trot out with you in hand? I think this is essential before ever ponying them; if she doesn't trot willingly inhand, she certainly won't do it being ponied, and you limited control (as you've noticed) to teach one to trot from up there.
I would also try teaching your other mare to neck rein better before ponying more too; This will make things even less complicated than if she has to be 'buggy reined'.
I pony our young mares a lot and this is very (very) good advice. If you can't comfortably ride your mare with one hand or just with your leg, I would seriously avoid even a dally until you and your mare have more experience ponying. The lead rope can quickly wind up wrapping around your hand or trapping your leg and, at best, it will hurt like #@$. Also, make sure you know how your mare will react (and if she is strong/balanced enough) if she is suddenly jerked when that lead tightens to the point where she is starting to 'drag' the other horse.
In general, keep a short lead and make sure she will consistantly stay at your hip at a walk before going to the trot. Like anything else, practice until the ponied horse knows that its 'job' is to be right there next to you, regardless of the gait.
Keep working on it as a team...it's a great riding skill to learn, and a good pony horse is worth it's weight in gold.