I am so glad you have aviacharge... you can mix that in with a wee bit of cooked oatmeal and then mix THAT in with their feed , freeing up the water for electrolytes or aspirin.
Ask the avian vet for meloxicam for pain... it can be used longer with less side effects than the aspirin. Also ask for (topical application) ivermectin ...it will address worms as well as most of those lice.
Unfortunately, they don't recognize oatmeal as food, maybe I'll try sprinkling some crumbles on oatmeal tomorrow. We did worm them with ivermectin today and switched them over to electrolytes. The one with the worst frostbite has all kinds of lice eggs stuck to her feathers under her neck, so we'll have to cross that bridge a bit later.
The vet didn't seem to think they needed pain medication and I can't handle another vet bill, so we've decided to leave it at electrolytes. Their feet (while still looking horribly nasty) are looking better. There is a bit of pink flesh and the swelling has gone done drastically. They are getting more active too and are ravenous. Their poops are looking normal and healthy, never knew I would spend so much of my time looking at chicken crap.
Hopefully all good signs. Once again, thanks for all the wonderful advice!