Hi AudeSpaere: I did a project a few years ago about all their BS doctrines and one of the subjects I did was on blood. Randy Watters has it on his Freeminds page and you can download it. It's in pdf. Go to pages 22 - 25 I believe and feel free to print it off and show it to your father.
When my brother in law was dying, I convinced him and my sister that the Organization's ban on blood tranfusions was absurd and completely without scriptural support. While they did end up taking blood, it was too little, too late for him. Out of frustration and rage at watching him slowly deteriorate, I phoned Bethel and spoke to some idiot in the Writing Dept. about the blood issue. I was prepared for every argument he had. Of course, he was more concerned about who I was and what congregation I went to than in dealing with the issue at hand. Finally at the end of the conversation when he had nothing to back his drivel up, he told me that "if any changes needed to happen, Jehovah would direct it through the "Slave". End of conversation. I really wish I had taped it.
There was someone else on here a couple of years ago who had a family member in the hospital and who was refusing blood. She emailed me about my project and I sent it to her. She printed it off and gave it to their daughter (the person in question) and apparently she read it, thought about it and decided to take the blood.
Here is the link: http://www.freeminds.org/index.php?option=com_content&view=article&id=758:marys-project-an-analysis-of-jehovahs-witness-doctrine&catid=11:bible&Itemid=698
Feel free to PM me as well.
Thanks to Scully for alerting me to this thread.