Can you please post some good clear photos of the hens, their legs and injuries?
How old are they?
I wouldn't mix the scratch grains with the all flock feed. Give the all flock free choice, a small amount of scratch as a treat.
If you are in the US, you can try giving human B-Complex once a day to see if that makes a difference. I would start with 1/4 tablet.
Hard to know if she can live the way she is or not - it depends on how well she can get about, what is causing the problem and if she's able to eat/drink well.
It can take time for injuries to heal.
Wonder how the rooster damaged the legs - did he get them penned up or did they run into something? Any other injuries to the head - the leg issues may be from nerve damage. I've had hens beat up, but they were always beaten about the head/face/neck - do these girls have any head injuries?