Some of my closest family members did not take it too well when I told them I was BP. And it was not to be talked about. It has taken my family a long time to accept that we have a strong genetic BP tendency, even with three generations of MI/BP in the family. Two to three in every generation. ( I have a big family, as well as a large extended family). It has caused me a lot of pain to deal with this. So my advice is to seriously consider what if your family does not respond well to this news. Prepare yourself mentally for a reaction from them that might be less than understanding. But I still think you should tell them. But maybe not everyone in the family. As for how? I just told them that I am bi-polar II. Some asked questions and some did not. The ones that asked me questions are the ones I feel I can trust in case something happens to me, because they at least have a rough knowledge of what is going on whith me. Keep it simple. Maybe advise them to take a look at some web-sites about BP? There is some information out there written from the perspective of familiy- members of people with BP, maybe asking them to take a look at some of them might be an idea?