Depends on some factors.. firstly one who is most wealthy and wishes to give it all for the other two members and donor's benefit of family and society.. and who can benefit the world by living.. and then who wants to live and has some commitment to fulfill.. ( in the case of 10 year old it would be the parents need for the child and in the case of 65 year old his children)..
And also who will live the maximum so the transplant is not just for short term gain.
Decision after weighing all factors.