You do have to use your head and watch the mares/foals. I've never really had them get tangled up, but they could. I HAVE had a loose foal rear up over a team (and not his dam which created a bit of a problem) and catch his legs in the harness! THAT was a mess that I sweated and shook over for some time, LOL. Funny now, but it sure wasn't when it happened. I wasn't alone, but my friend was too far away to help right then. I had him loose before she got to us. IF I was a smoker, I'd of needed a cigarette right away!!!
I really like taking the babies with me for driving. They "teach themselves" to lead w/o ME involved, LOL - just them, the rope and their dam (whom they want to follow usually). Also, I SEE A BIG DIFFERENCE when I now go on to teach those foals to drive. Just easier - they've already been around the wheeled vehicles, they hear the different sounds they make, also get used to straps over them and around them and the jingling the work harness makes.
With our riding ponies and horses, our mares were often ridden literally not long after they gave birth! Our mares have always been "working mares" and that means that they were lesson mounts, or riding mounts for our daughters or what ever... The mares were ridden regularly thruout the pregnancy and then as early as hours after giving birth. The riding/work was adjusted to what the mare and/or foal could handle. Here are some pics.
Just hours old. Cherokee is 1/2 Shetland.
1 week old. I led "Frosty" from the ground the 2 miles to the barn as his dam can't stand ropes around her body nor did this daughter of our EVER develop the ability to pony another horse from the one she was riding. Frosty is a purebred Shetland.
Blizzard was born the 25th of January. This is the 5th of Feb and I guess I lied - the lead is hooked directly to his halter here... Blizzard is 1/2 Shetland.
Vixen was born the 10th of May. And years later, our youngest daughter rode Vixen to pony Vixen's 1/2 sister, Star.
and then Star with her own daughter (didn't get pics when Flower was younger)