From bpso list discussion
For the person who is struggling with a decision about what and how to share - with family members - information about a loved one's diagnosed mental illness:
A couple of thoughts --
1) privacy -- many of us treat the family member with the diagnosis like we should keep their "secret" of mental illness. In some ways this seems respectful of their privacy, a concept enshrined by our legal and medical professions with some good reason, but within the family, I personally believe that anyone who has substantial contact with a family member suffering from a mental illness has a right to know about the illness, and a responsibility to understand it fully and learn how to cope appropriately. Perhaps your have experienced a situation where a family member feels a little betrayed that no one filled them in about this before they had a visit with the mentally ill relative. Honesty is the best policy -- maybe you can explain that you considered sharing information about the diagnosis/illness, and hoped nothing would happen because you so badly wanted them to get along. You could apologize and explain that you see in retrospect that maybe this wasn't the best choice.
2) forgiveness -- sometimes when we tell a person about a loved one's illness and bad behavior, it sounds like we are making excuses and asking others to tolerate bad behavior. One must be careful how to frame this to family members. I believe it's reasonable to ask that they understand that the bad behavior is not necessarily caused by the loved one's animus toward family member or a "will" to do something bad. Bipolar Disorder causes distorted, irrational decision-making and impulsivity. So, while the loved one may have "decided" to steal (or drink or have an affair or fill-in-the-blank), that "decision" isn't the same kind of rational decision that you or I might make, nor does the loved one necessarily have the same kind of impulse control that they might restrain themselves in the way you or I might. That said, a family member doesn't have any obligation to continue to subject themselves to bad behavior. It might help to have a serious conversation with an affected family member in which you explain in detail about how Bipolar Disorder can affect behavior and ask them not to see your loved one as a bad person or a person who wants to deliberately hurt them, but also acknowledge that they (with your help) might need to rethink how the family member can productively (and safely) have a relationship with the loved one. Maybe overnight visits are not a reasonable expectation with a mentally ill person.
3) Encourage family members to find the NAMI Family to Family course in her area (find out more at nami.org). It is really a great class to teach family members of the mentally ill about bipolar disorder and to help family members understand what it's like to be ill, while also empowering them to think about how to structure their relationship with the ill person. I personally believe that every family member of a mentally ill person has a responsibility to learn about bipolar disorder as much as they can -- there are also some great books.