Bad feelings are one thing. But refusing to donate bone marrow that could save someone's life is something else. I don't care how much she hates her brother, this is truly inhuman.
This woman is just hard and cold. If she weren't, how about, "I'm sorry, I would dearly love to help save your life, but it's not physicall [or whatever] possible."
I hope her business dries up and everyone in England knows how selfish and evil she is if she truly "won't" help.
There are really only three reasons the sister would not donate at this point,IMHO.
1.A contrived politically oriented reason:Use this situation to write new laws compelling forced organ/cell donations for best transplant matches.
2.Personal family reasons, that are none of our business, but reflect very badly on the brother.
3.Personal family reasons, that are none of our business, but reflect very badly on the sister.
Not enough information is available to decide which of the above three apply, at this point.
The choice of language and phrasing from the recipient I characterize as equally inhuman.
If one successfully can intimidate another this way, it would be just a short step until we reach the bottom of that slippery slope.
My brother and I are estranged...my choice because he's a lying thieving creep...but even so, if he or his children were in a situation like this gentleman, I would donate whatever they needed to save a life. I refuse to dishonor my parents by behaving any other way.