Have you checked to see if the leg is swollen or if it looks/feels broken?
Can you take a short video of how she tries to walk and upload it to YouTube?
Oats isn't going to cut it.
Do you have poultry vitamins like Nutri-Drench?
Unless you have the new birds a football field length away and practice strict biosecurity it doesn't really matter if they aren't housed together.
Where did the new birds come from and how old are they?
I am so sorry.
She may have been full of worms because her immune system was already taxed so to speak.
Have you brought home any new birds in the last few months?
Is she eating a complete balanced food right now?
I just skimmed some of your other posts.
How old is this sick one?
How many days has she not been eating?
Is she one that you've been treated with Corid too?
Type in tube feeding on YouTube JUST to get an idea if it is something you can do.
If so I'll call over someone to help you.
Do not follow any video...just use them to get an idea if you can gather the supplies and physically do it.