Help! Family crisis!

I could use some input on how to help alleviate a family crisis I inadvertantly started. Here's the background:

I have a favorite Uncle whom we call Buddy. Buddy is a 59 YO widower, a great fun-loving grandfather who is in perfect health. Buddy has five kids, four brothers and a sister ranging in age from 39 to 25. Child #2 is my cousin Mark, the ne'er-do-well of the family. Mark has had problems with drugs and booze, has done three years of jail time for a series of robberies and has three children (whom he has rarely seen or supported) with two women, neither of whom he married. In early 2000, Mark learned that his kidneys were starting to fail, a result of years of self-abuse and abnormally high blood pressure that was never effectively treated. Mid-last year, Mark's condition had degraded to a point where he was diagnosed with end stage renal failure. In short, without a kidney transplant, Mark -- who has no health insurance -- was doomed to dialysis, debt and probable death before he reached 40.

This health news helped Mark get scared straight. He kicked the booze and drugs and has been sober since August. He found a part time job that can fit around his dialysis schedule (3X a week, 3 to 4 hours a pop). And he's started to try to be a father to his children. But despite this turnaround, when Mark went looking to his family for possible kidney donors, three of his siblings refused to even consider it. Too much relationship damage had been done over the years. Only his youngest brother Joe was open to the idea but he isn't eligible because he has Type I diabetes. My cousin Joe is a truly great guy -- devoted husband and father, volunteer fireman, sunday school teacher -- just the sort of guy who wouldn't think twice about donating an organ to someone in need. But with Joe out as an option due to diabetes, Mark turned to his father Buddy. Once assured by his doctor that his age was not an issue, Buddy agreed to be tested to see if he was a match. If the tests were positive, he promised to donate his kidney to Mark. Mark and Joe were ecstatic but my other cousins were furious. And, more to the point, I sensed a little reluctance on the part of Buddy. Mark is his son, and he loves him, but Mark has really put Buddy through the wringer over the years. When my aunt died of a heart attack at age 52, it didn't take much to figure out that Buddy felt Mark was largely to blame.

Meanwhile, "good" cousin Joe had one of his regular doctor's appointments for his diabetes where he mentioned that his father was going to donate his kidney to his brother Mark. This news caused the doctor to remind Joe that he could very likely need his own transplant someday given the high rate of kidney failure in Type 1 diabetics. I had lunch with Joe the next day (right around Christmas) when he mentioned the irony of Mark needing a kidney instead of him. Joe had not told his father about this potential future need on his part, so later that night, I told Buddy this news. In my mind, I rationalized this stupid act as being "fair" to Buddy but, in reality, I just created a huge mess. At Christmas dinner, Uncle Buddy announced that, while he was in fact a positive donor match for Mark, he had changed his mind. He wanted to keep the kidney in case Joe might need it some day.

Since Christmas, things have been incredibly emotional and tense. Neither Mark nor Joe are speaking to me. Buddy seems more steadfast in his refusal than ever -- he's convinced that Mark's "selfish" disappointment is just more proof that he doesn't deserve the organ. My other cousins are standing firmly behind their father and he won't listen to my arguments. While never the tightest of families before, they are now completely divided. Meanwhile, Mark is not doing well at all -- he's on organ waiting lists but his history is keeping him far from the top. And I feel terrible because this is largely my fault.

So, there's the predicament. Any ideas to fix the situation? Any suggestions would be greatly appreciated.