Wet it and braid it in sections over night or as long as it takes to train itself. Wet it, braid it and then but a hot cloth over the braids for about 7 mins. Then leave them in over a few nights and repeat if needed
Banding ☀️ You can find some inspiration at HorseGroom Denmark at Facebook 🐎
Banding your horses mane trains it to stay on one side if u do it consistently. It's hard to do so you might need help :) ^^^^
Use a hot towel every time you groom! This will help it lay flat along with what Lauryn said above.
Braid it all to one side like you're going to do button braids, but don't sew them up, leave them hanging. Only take them out every once in a while and when it rains