"I have never seen the distinction made that if it is to be used for fractions, it is permissible. I would like for this to be so."
I haven't done this in several years, but at one time a JW could phone Bethel and ask "Since we can accept fractions from blood that has been donated by someone can we donate blood strictly for the purpose of having fractions extracted for another JW who needs it for transfusion?" and they'd get the answer, "Yes, so long as the rest is thrown away."
Once when I spoke with insider Fred Rusk I went further by asking why this was not published information. His response haunts me to this day. He said, "It's not something we want to talk up."