I commend you on your heart.
However, I would like to respectfully comment in a different light.
If these birds were moved from a climate-controlled environment eating an appropriate, nutritionally formulated diet to new food, a new environment of potential pathogens while under incredible stress during mid-moult in fall when temps are cooling...how could they be expected to thrive, or even survive? The introduction to new Eimeria strains may be a tax on their systems. The change of diet plus adding other strange foods and additives may have wreaked havoc on their gut microbiota and left them extremely compromised. In their weakened state, they've been exposed to cold temperatures with wind...and potential pathogens.
Here is some information regarding the chicken GI tract and the microbiome.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6206279/#:~:text=The GI tract of the chicken includes the crop, proventriculus,, and cloaca (32).&text=The majority of bacteria in,and coliform bacteria (28).
Here is an overview of Necrotic Enteritis in Poultry.
https://www.merckvetmanual.com/poul...ecrotic-enteritis-in-poultry?redirectid=22935
An overview of coccidiosis in poultry.
https://www.merckvetmanual.com/poultry/coccidiosis/overview-of-coccidiosis-in-poultry
1) If you could provide the feed these birds were previously fed, that may help. If not, providing a non medicated chick starter might be helpful.  A new food can be slowly introduced over a period of time to acclimate the gut microbiota once the hens have recovered fully.
2) Coccidiosis may be an issue. Consult a vet and provide the hens with a prescribed coccidiostat if required. Medicated feed usually won't contain enough medication to be properly effective.
3) Keep the birds in their coop until they're well. While everyone thinks it's kind and wonderful to let the birds outside to experience the outdoors; they're not acclimated to the temperatures or the weather and being exposed so quickly will be a great source of stress and fear for a prey species. Limiting stress and providing a warm and safe atmosphere is paramount.
4) Keep all stresses to a minimum for an extended length of time.