When you receive a transplant and wish to thank the donor family, it is done through the transplant co-ordinators. You can write a letter giving them a bit of information about you but nothing too specific at first, only first names and general location. Your full details need to be enclosed...
I was one of the lucky people to receive a transplant in May 2007 which has so far proved to be successfull in (temprarily) curing me of Diabetes Mellitus. So far, touch wood, I have had no hypos/hypers and the complications I suffered whilst diabetic have reduced in severity or disappeared...