I think this all sounds like an unfortunate situation. But I really can’t get over the fact that it sounds like OP told the kids that “this was THEIR pony” before the deal was done (meaning, before you got her home safe and sound and all paperwork was a done deal). Huge red flag to me that your daughter was calling it “her” pony after a few phone conversations - yikes! Definitely putting the cart before the horse and not cute at all.
I leased my (first) horse out when I was 12 or 13 and I’ll never forget the family leasing the horse coming out and going on and on about how he was now THEIR horse and talking baby talk to him about how he finally had a mommy (and so on). I was a wreck. I knew we needed to lease out the horse, but the “he’s MINE now! MINE MINE MINE!” was really hard to take at that age. My parents pulled the brakes for a couple of weeks on the lease because they could see how upset I was (and how insensitive the new family was). Financially we had to do it and we did, but I could see how a different parent might lean the other way and change their mind entirely.
But back to the dealing with your own kid part. I have a kid and have purchased the kid a pony. I wouldn’t dream of telling her that a pony was hers while it was still at another farm. Even if we were going to try out a pony and she knew that it was for her the conversation all the way there would revolve around not getting her hopes up and continually restating that we’re just TRYING the pony. It might not work out for a million different reasons and boy have I seen things fall apart for that many reasons. I would (and have) reiterated again and again that the pony belongs to the people at the farm. Calling it “yours” is insensitive at best and frankly outright rude, even if you’re all just trying to be cutesy.
I agree that it doesn’t sound like you have much experience in the horse world. And this thread sounds like a passive aggressive way to “out” the seller and start a fight online. There’s no “warning” here, other than that which others have pointed out (don’t count your chickens before they hatch), which is so obvious that you seem to be the only one who’s missed the point.
I feel sorry for your kids and the disappointment I’m sure they felt, and it doesn’t sound like the seller handled things as well as she could have, but wow, the real failure to me sounds like this whole ill-fated family trip to get the pony without any backup plan in case it didn’t work out. You’re blaming the seller for letting down your kids, but at the end of the day YOU are the one who let down your kids by building up their expectations to start with. The seller may not have behaved perfectly (without hearing the other side of the story I’m hesitant to say anything and I realize that she could be anywhere along the spectrum of an innocent person watching out for her pony to a total scam artist), but at the end of the day the only person who’s going to protect your children from a situation like this is YOU.
So while I hope that perhaps this thread helps out someone else guilty of getting ahead of themselves, I really hope that writing it all out helps you figure out a better way to deal with a transaction involving kids and ponies.
