She's getting free choice hay along with the other stuff? You're building her up to more beet pulp, etc? Is she turned out or stalled? If cooped up I'd get her out asap. Ensuring her teeth are in good order & she's *effectively wormed is of course important. If she's been starved, I'd also consider adding a probiotic &/or ulcer treatment & avoid giving her any grain or otherwise starchy feed. I'd also feed as little & often as possible.
Great you're getting a chiro for her - not sure if her lack of condition is making it look worse, but there's something going on in that lumbar-sacral area. But it looks like her hoof confo has probably been that way for some time, so she may also need front end work(tho maybe soft tissue, not chiro) combined with good hoof care to improve it.
Hope you have a good farrier/trimmer coming - her feet are desperate for attention too! I wouldn't be inclined to put shoes on her, at least until they can get healthier. Need better pics to say too much, but it looks like she could possibly be a bit laminitic - many other reasons than obesity that horses can suffer this, including mechanics. Her toes appear flared & ringed & her heels are huge but also way forward. So she's up on her toes like stillettos, which is why she's forward at the knee. Her legs being unable to lock straight, means that she won't be able to rest properly standing up.