I'm sure this is terribly difficult time for you and your family. I suggest that you search on line about liver failure as well as stages of dying. As hard as it is, sometimes knowing what to expect can be helpful. Peace to you.
I'm so sorry to hear about your sister. That must be a difficult thing to go through.
This is a forum for people who are LIVING with Hepatitis B. I'm not sure if there are support groups for relatives of Hep B patients. Certainly a grief support group might be helpful.
Best wishes.
I wish I could help but what I know is so limited.
Depending on what you mean by "liver failure," what to expect can be very different. If decompensated liver disease develops (defined as the onset of ascites, encephalopathy, or variceal bleeding), the death rate increases dramatically. I hope your sister is better than what you think and her doctor still has treatment options to help her.
Meanwhile, the 14-year-old girl and you need to be checked for possible vaccination.
Hope this helps.