You're work sounds amazing, and good luck with the foal! You're thoroughbred looks gorgeous <3 And if you would like to halter train the Belgian first, I'd try running the halter with some peppermint oil, seeing as horses love the smell of peppermint. When haltering, have a treat in hand when your horse slips through the nose band, that way they're being rewarded right away. It's sort of tempting him in a way, but after a couple of more times doing this you can stop with the treats.