I've heard that you can syringe-feed chickens (although it's a bit riskier than mammals because chickens don't have throat muscles). I've never done this before, but I think it would be a topic to consider since she has a broken jaw. So since she suffered some torn scalp and a broken jaw, the rooster was very violent towards her?
Look up crop tube feeding on the forum. There are instructions on how it is done. You can pick up aquarium tubing if you have trouble finding a crop tube. One thing you want to make sure you do is don't forget to give the bird proper hydration with water before feeding. You can search that also on how much water a bird should have depending on it's size. May not need as much water if the diet is liquid anyway. I have used jar baby food and baby cereals with a little yolk mixed with the water to feed birds with a tube. Moves easier through the syringe and tube. Something to consider when you run out of the baby bird food.