This is "clear and convincing" evidence. The highest burden of proof in civil law. Okey-dokey.
In the Weekly Standard, Wesley Smith offers up a survey of the evidence supporting the claim Terri Schiavo wanted her food and water yanked.
ONE EVENING, during the second term of President Ronald Reagan, Terri Schiavo and her husband Michael decided to watch a television movie about Karen Ann Quinlan. Quinlan, as most readers know, had a tragic life. After overdosing on a combination of drugs and alcohol, she fell into unconsciousness and never awakened. Her parents won a lawsuit in the New Jersey Supreme Court allowing them to disconnect her ventilator. Karen didn't die immediately--she lived on for 10 more years before finally expiring from pneumonia.
While discussing the movie, Michael claims that Terri stated she would not want to live hooked up to a "machine" (she's not), or be a "burden" (her parents don't consider her a burden and want to care for her). Michael's brother, Scott, backs up his claim, while his sister-in-law, Joan, told the court that Terri had approved of pulling the life support from the dying baby of a mutual friend and said that if she ever wrote a "will" she would say that she didn't want "tubes."
Little did Terri know that these purported statements, uttered under very casual circumstances, would become the justification used by her husband in his six-year drive to remove her feeding tube and end her life. Indeed, based on these casual statements, Judge George Greer of the Sixth Judicial Circuit in Clearwater, Florida ruled that Michael had established "by clear and convincing evidence"--the highest evidentiary standard in civil law--that Terri would rather dehydrate to death over a period of 10-14 days than live on food and water supplied by a feeding tube.
Maybe you should do something like this. Otherwise, you might want to review all your conversations on end-of-life issues since, oh, you turned 18, and start correcting any potential misunderstandings. Right now.