De donor

Will Marion has two perfect kidneys. His daughters aren't so lucky. Question is: which one should he save? Will's 47. His wife bailed out when the twins were in nappies and hasn't been seen since. He coped OK by himself at first, giving Georgie and Kay all the love he could, working in a boring admin job to support them. Just after the twins turn sixteen, Georgie suffers kidney failure and is placed on dialysis. Her type is rare, and Will immediately offers to donate an organ. Without a transplant, she would probably never see adulthood. So far so good. But then Kay gets sick. She's also sixteen. Just as precious. Her kidney type just as rare. Time is critical, and he has to make a decision. Should be buy a kidney - be an organ tourist? Should be save one child? If so, which one? Should be sacrifice himself? Or is there a fourth solution - one so terrible it has never even crossed his mind?