So sorry for what you're going through. It has to be the hardest thing ever to watch someone you love slowing dying while refusing life saving treatment.
Are you up to date on their policies? The reason I ask is because they change SO often. There was a time they didn't allow organ transplants. Now they do. They didn't allow ANY blood that I know of, but now they allow many, if not most of the parts or fractions of blood.
Found this on a quick search:
"Also referred to as “thrombocytes”, they are specialized blood cells
responsible for stopping bleeding. Like the red cell, they have no
nucleus. They are the smallest of the blood components, amounting to far
less than 1% of blood volume, yet they remain banned. They are used to
treat Thrombocytopenia, side effects of chemotherapy or a low platelet
count due to lumbar puncture or bone marrow aspiration. The platelet is
banned for Jehovah’s Witnesses but like the red and white cell,
everything within it are permitted."
http://ajwrb.org/watchtower-approved-blood-transfusions
Would, or could, the Dr. dance to their tune and separate the fractions before giving them to her? You've probably already researched, but if you haven't, I'd dig into the WTS literature and you might find a life saving "loophole".
My heart goes out to you and you'll be in my thoughts. Hoping some research will convince her that she can take some life saving measures.