Yes, she can develop a hay belly.... But you just have to do the best you can with the situation you have. How many other goats are in her pen (I can't find the post where you had discussed it previously)? It is going to get expensive to feed Calf Manna to all of them at a rate to benefit just one... I wish you were able to separate her out into a pen with just her and another goat, so you had better control of feeding her.
Another contributor to the "hay belly" look can be worms.... And with a bunch of goats sharing 1 pen it raises the chances of parasite load... Lots of factors to consider such as size of pen, footing, feeding stations/areas, lot rotation, fecals, worming protocol, etc.... Do you have a parasite control program in place?
We have a few >2yr old breeding does that we can literally pull straight off the pasture, shine them up, and be competitive with them. But our junior - senior - yearling does we try to "get fit" alongside our market kids. They get walked (or run for short distances if they are feeling spicy) multiple times a day. The junior does bulk up, but the seniors & yearlings just seem to get "toned" and less soft. We just compete within the state of Maryland, so we are not uber-competitive, but for being home-raised Boers that keep getting further and further out from their Ennobled pedigrees, we do okay. Kids born spring 2017 will be 3 generations out from full Ennobled parentage. Most of our competition is first generation from Ennobled (several local families have $xx,xxx Ennobled bucks as herd sires).
There are 2 pens and 6 goats including her. I think that I could get her to go in with 1 other goat and have 4 in the other side. That would be ideal. But worst case scenario is she's in with 2 others. Thats not too bad. I worm my goats too. So I don't think worms should be an issue. Their pen is probably....30' x 80'? With 3 goats. The feed and water is all next to each other by the fence. They stay on that lot 365 days a year. The footing is firm everywhere but soggy in the first 30x30 section of the pen where they hang out.
I'm not working with amazing genetics here....the best she's got is her great grand sire is chicken on a chain. So she is far removed from ennobled genetics. Also another one of her great grand sires is ennobled too. But I forget their name. Hopefully I can pull her out of the pen and she'll be decently competitive! Any advice would be appreciated.