I will try my best, but lets just say I have a stubborn relative who refuses to accept a confirmed diagnosis of primary generalized seizures. My father is extremely difficult to deal with, and first day I went to see the neurologist, he was complaining on the way home about it. He still doesn't think it is epilepsy, even though the EEG confirmed it.
What I did was when he went into the office I explained to the neurologist how he doesn't accept it, and assumes it's other things as syncope, sleep apnea, and other conditions and my dad got extremely angry over that. The neurologist explained it to him though in simple terms so he could understand, but he still doesn't believe the doctor. The doctor even told him why I make noises when I have seizures, and why it isn't sleep apnea.
I finally bought a book, epilepsy 101 The Ultimate Guide for patients and Families Perfect, and still he didn't acknowledge and assumes it's my life style instead of epilepsy. I usually showed him youtube, research, videos of seizures, and so forth and he assumes that it's garbage and lies. I even showed him Hippocrates on the sacred disease talking about epilepsy, then he got offended because he talked about religion...
Perhaps you can educate them using one of these steps, it didn't help me. I wish people wouldn't be so close minded... Oh well though.