So sorry you and your little ones are going through this. I don't have much advice for Cher but diet can play a role in the management of liver problems. A lower protein level, but of a very high quality can help to lessen the stress on the liver and reduce the ammonia levels that build up in the body when the liver is failing. The problem is that if she's not eating it doesn't matter what diet you're trying to feed her
There are other drugs and some antibiotics that can also be used to modify the gut flora and reduce the ammonia and toxic metabolite levels which make them feel really grotty. I really hope she feels better soon. Hugs to both your girls and a hug for you too.