Education. If they are willing it sounds like they need a more comprehensive understanding of fibromyalgia. If you offer materials or articles to read and they are not interested then you have no further obligation. Their anger is theirs. Don't feel guilty for making them angry and don't make their anger your responsibility.

Thank you!! This is very helpful!! I have offered some materials but one of my family members (a sibling) gets mad every time I bring it up. I’m going to work on not feeling guilty for making them angry and I won’t make their anger my responsibility. Thank you again!!