@mahdi123, I was diagnosed with liver disease nearly 8 years (2002?)before my gastroenterologist sent me to the transplant department for transplant evaluation. During those years, he monitored my condition thru routine (4 month) labs and office appointments.
My liver function numbers were stable for the most part, then a slow steady rise in liver function labs began at the same time as bothersome symptoms -itching, nausea, more fatigue.
In September 2008, I had my 1st appointment with transplant dept. They examined me and did some scans and labs. The transplant doctor said I would be eligible for a liver transplant because my MELD score of 15 was the minimum to be listed for a liver at that particular time. My evaluation tests were in November, and I was added to the transplant list. Then (in my case) I declined steadily. I transplanted in April 2009. Not everyone follows the same path. I think that my fast decline surprised my doctors.

What has your sister's doctor said about when/if she will need transplant? How is she feeling?