When you have a hen that is aggressive, you can show her that you are the top hen and you won't tolerate it.
What I do is to grab a hen as soon as she even approaches me with that mean look in her eye, or starts to attack, and hold her down with my hands, so that she is resting on the ground...
https://www.backyardchickens.com/t/802884/wry-neck-and-heat#post_11605165
I just wrote a post #2 here if you would like to look...my info. on wry neck is almost wholly from reading- I have no experience with wry neck except an injury and it only lasted 24-48 hours.
You said the chickens won't be fit to eat. Actually with Wazine, it's the egglayers that it isn't labeled for. See the deworming link in post #8025- it mentions broilers.
Edited- I went back and found the info for slaughter (there is a withdrawal time):
http://www.drugs.com/vet/wazine-17.html...
http://www.healthybirds.umd.edu/disease/deworming%20birds.pdf
Wazine is the only medication currently approved for poultry deworming. It is NOT approved for egglayers, however. There is NO medication approved for egglayers. So you would be going off-label to deworm your layers.
On BYC most...