I agree with red. These things can happen very suddenly--an esophageal hemorrhage can cause death in minutes. OTOH, my second husband is, somehow, still alive almost 20 years later. He must be in truly awful shape, but he's alive. So pass along the info from the doctors and let your sister make the call. No matter what happens, neither of you have anything to feel guilty about. You can't hover over her for the rest of her life--however short/long that may be--to be sure you are there for her final moments.