I found that when we explain something to another person it is important to make good use of 'what-if situation.'
If an old man, say, is informed that he has cancer but his daughter doesn't know he has been driven into such a bad situation, she may assert that his doctor should have informed her of her father's cancer, when she gets to know the truth.
Now, the doctor inquire of her what if she would be put in the same situation.
Would she really let her family know her condition?
まぁ、どうでもいいけどね、そこらへんは。